diff --git a/errs/error.go b/errs/error.go
deleted file mode 100644
index f6a6bfb..0000000
--- a/errs/error.go
+++ /dev/null
@@ -1,75 +0,0 @@
-package errs
-
-import (
-	"encoding/json"
-	"fmt"
-	"strconv"
-)
-
-// Error returns the string representation of the error and satisfies the error interface.
-func (f *Failure) Error() string {
-	if f != nil && f.runtimeErr != nil {
-		return f.runtimeErr.Error()
-	}
-
-	return ""
-}
-
-// ApiError returns formatted string representation of the API error
-func (f *Failure) ApiError() string {
-	if f != nil && f.apiErr != "" {
-		return fmt.Sprintf("%+v", f.apiErr)
-	}
-
-	return ""
-}
-
-// ApiErrors returns array of formatted strings that represents API errors
-func (f *Failure) ApiErrors() map[string]string {
-	if len(f.apiErrs) > 0 {
-		return f.apiErrs
-	}
-
-	return nil
-}
-
-// SetRuntimeError set runtime error value
-func (f *Failure) SetRuntimeError(e error) {
-	f.runtimeErr = e
-}
-
-// SetApiError set api error value
-func (f *Failure) SetApiError(e string) {
-	f.apiErr = e
-}
-
-// SetApiErrors set api errors value
-func (f *Failure) SetApiErrors(e map[string]string) {
-	f.apiErrs = e
-}
-
-// ErrorsHandler returns map
-func ErrorsHandler(errs interface{}) map[string]string {
-	m := make(map[string]string)
-
-	switch errs.(type) {
-	case map[string]interface{}:
-		for idx, val := range errs.(map[string]interface{}) {
-			m[idx] = val.(string)
-		}
-	case []interface{}:
-		for idx, val := range errs.([]interface{}) {
-			m[strconv.Itoa(idx)] = val.(string)
-		}
-	}
-
-	return m
-}
-
-// ErrorResponse method
-func ErrorResponse(data []byte) (FailureResponse, error) {
-	var resp FailureResponse
-	err := json.Unmarshal(data, &resp)
-
-	return resp, err
-}
diff --git a/errs/error_test.go b/errs/error_test.go
deleted file mode 100644
index 20d38d0..0000000
--- a/errs/error_test.go
+++ /dev/null
@@ -1,50 +0,0 @@
-package errs
-
-import (
-	"reflect"
-	"testing"
-)
-
-func TestFailure_ApiErrorsSlice(t *testing.T) {
-	var err = Failure{}
-	b := []byte(`{"success": false, "errorMsg": "Failed to activate module", "errors": ["Your account has insufficient funds to activate integration module"]}`)
-	expected := map[string]string{
-		"0": "Your account has insufficient funds to activate integration module",
-	}
-
-	resp, e := ErrorResponse(b)
-	err.SetRuntimeError(e)
-	err.SetApiError(resp.ErrorMsg)
-
-	if resp.Errors != nil {
-		err.SetApiErrors(ErrorsHandler(resp.Errors))
-	}
-
-	eq := reflect.DeepEqual(expected, err.ApiErrors())
-
-	if eq != true {
-		t.Errorf("%+v", eq)
-	}
-}
-
-func TestFailure_ApiErrorsMap(t *testing.T) {
-	var err = Failure{}
-	b := []byte(`{"success": false, "errorMsg": "Failed to activate module", "errors": {"id": "ID must be an integer"}}`)
-	expected := map[string]string{
-		"id": "ID must be an integer",
-	}
-
-	resp, e := ErrorResponse(b)
-	err.SetRuntimeError(e)
-	err.SetApiError(resp.ErrorMsg)
-
-	if resp.Errors != nil {
-		err.SetApiErrors(ErrorsHandler(resp.Errors))
-	}
-
-	eq := reflect.DeepEqual(expected, err.ApiErrors())
-
-	if eq != true {
-		t.Errorf("%+v", eq)
-	}
-}
diff --git a/errs/interfaces.go b/errs/interfaces.go
deleted file mode 100644
index 371eec4..0000000
--- a/errs/interfaces.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package errs
-
-// Error implements generic error interface
-type Error interface {
-	error
-	ApiError() string
-	ApiErrors() map[string]string
-}
diff --git a/errs/types.go b/errs/types.go
deleted file mode 100644
index 5af2e43..0000000
--- a/errs/types.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package errs
-
-// Failure struct implode runtime & api errors
-type Failure struct {
-	runtimeErr error
-	apiErr     string
-	apiErrs    map[string]string
-}
-
-// FailureResponse convert json error response into object
-type FailureResponse struct {
-	ErrorMsg string      `json:"errorMsg,omitempty"`
-	Errors   interface{} `json:"errors,omitempty"`
-}
diff --git a/go.mod b/go.mod
index 2c5d926..186f5f0 100644
--- a/go.mod
+++ b/go.mod
@@ -5,5 +5,6 @@ go 1.13
 require (
 	github.com/google/go-querystring v1.1.0
 	github.com/joho/godotenv v1.3.0
+	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543
 	gopkg.in/h2non/gock.v1 v1.0.16
 )
diff --git a/v5/client.go b/v5/client.go
index 6978762..122e200 100644
--- a/v5/client.go
+++ b/v5/client.go
@@ -15,10 +15,9 @@ import (
 	"time"
 
 	"github.com/google/go-querystring/query"
-	"github.com/retailcrm/api-client-go/errs"
 )
 
-// New initialize client
+// New initialize client.
 func New(url string, key string) *Client {
 	return &Client{
 		URL:        url,
@@ -27,11 +26,11 @@ func New(url string, key string) *Client {
 	}
 }
 
-// GetRequest implements GET Request
-func (c *Client) GetRequest(urlWithParameters string, versioned ...bool) ([]byte, int, *errs.Failure) {
+// GetRequest implements GET Request.
+func (c *Client) GetRequest(urlWithParameters string, versioned ...bool) ([]byte, int, error) {
 	var res []byte
 	var prefix = "/api/v5"
-	failure := &errs.Failure{}
+	apiError := &APIError{}
 
 	if len(versioned) > 0 {
 		s := versioned[0]
@@ -43,8 +42,7 @@ func (c *Client) GetRequest(urlWithParameters string, versioned ...bool) ([]byte
 
 	req, err := http.NewRequest("GET", fmt.Sprintf("%s%s%s", c.URL, prefix, urlWithParameters), nil)
 	if err != nil {
-		failure.SetRuntimeError(err)
-		return res, 0, failure
+		return res, 0, err
 	}
 
 	req.Header.Set("X-API-KEY", c.Key)
@@ -55,37 +53,43 @@ func (c *Client) GetRequest(urlWithParameters string, versioned ...bool) ([]byte
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
-		failure.SetRuntimeError(err)
-		return res, 0, failure
+		return res, 0, err
 	}
 
 	if resp.StatusCode >= http.StatusInternalServerError {
-		failure.SetApiError(fmt.Sprintf("HTTP request error. Status code: %d.\n", resp.StatusCode))
-		return res, resp.StatusCode, failure
+		apiError.ErrorMsg = fmt.Sprintf("HTTP request error. Status code: %d.\n", resp.StatusCode)
+		return res, resp.StatusCode, apiError
 	}
 
 	res, err = buildRawResponse(resp)
 	if err != nil {
-		failure.SetRuntimeError(err)
+		return res, 0, err
+	}
+
+	if resp.StatusCode >= http.StatusBadRequest && resp.StatusCode < http.StatusInternalServerError {
+		return res, resp.StatusCode, NewAPIError(res)
 	}
 
 	if c.Debug {
 		log.Printf("API Response: %s", res)
 	}
 
-	return res, resp.StatusCode, failure
+	return res, resp.StatusCode, nil
 }
 
-// PostRequest implements POST Request with generic body data
-func (c *Client) PostRequest(uri string, postData interface{}, contType ...string) ([]byte, int, *errs.Failure) {
+// PostRequest implements POST Request with generic body data.
+func (c *Client) PostRequest(
+	uri string,
+	postData interface{},
+	contType ...string,
+) ([]byte, int, error) {
 	var (
 		res         []byte
 		contentType string
-		reader      io.Reader
 	)
 
 	prefix := "/api/v5"
-	failure := &errs.Failure{}
+	apiError := &APIError{}
 
 	if len(contType) > 0 {
 		contentType = contType[0]
@@ -93,22 +97,14 @@ func (c *Client) PostRequest(uri string, postData interface{}, contType ...strin
 		contentType = "application/x-www-form-urlencoded"
 	}
 
-	switch postData.(type) {
-	case url.Values:
-		reader = strings.NewReader(postData.(url.Values).Encode())
-	default:
-		if i, ok := postData.(io.Reader); ok {
-			reader = i
-		} else {
-			failure.SetRuntimeError(errors.New("postData should be url.Values or implement io.Reader"))
-			return []byte{}, 0, failure
-		}
+	reader, err := getReaderForPostData(postData)
+	if err != nil {
+		return res, 0, err
 	}
 
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s%s%s", c.URL, prefix, uri), reader)
 	if err != nil {
-		failure.SetRuntimeError(err)
-		return res, 0, failure
+		return res, 0, err
 	}
 
 	req.Header.Set("Content-Type", contentType)
@@ -120,26 +116,46 @@ func (c *Client) PostRequest(uri string, postData interface{}, contType ...strin
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
-		failure.SetRuntimeError(err)
-		return res, 0, failure
+		return res, 0, err
 	}
 
 	if resp.StatusCode >= http.StatusInternalServerError {
-		failure.SetApiError(fmt.Sprintf("HTTP request error. Status code: %d.\n", resp.StatusCode))
-		return res, resp.StatusCode, failure
+		apiError.ErrorMsg = fmt.Sprintf("HTTP request error. Status code: %d.\n", resp.StatusCode)
+		return res, resp.StatusCode, apiError
 	}
 
 	res, err = buildRawResponse(resp)
 	if err != nil {
-		failure.SetRuntimeError(err)
-		return res, 0, failure
+		return res, 0, err
+	}
+
+	if resp.StatusCode >= http.StatusBadRequest && resp.StatusCode < http.StatusInternalServerError {
+		return res, resp.StatusCode, NewAPIError(res)
 	}
 
 	if c.Debug {
 		log.Printf("API Response: %s", res)
 	}
 
-	return res, resp.StatusCode, failure
+	return res, resp.StatusCode, nil
+}
+
+func getReaderForPostData(postData interface{}) (io.Reader, error) {
+	var reader io.Reader
+
+	switch d := postData.(type) {
+	case url.Values:
+		reader = strings.NewReader(d.Encode())
+	default:
+		if i, ok := d.(io.Reader); ok {
+			reader = i
+		} else {
+			err := errors.New("postData should be url.Values or implement io.Reader")
+			return nil, err
+		}
+	}
+
+	return reader, nil
 }
 
 func buildRawResponse(resp *http.Response) ([]byte, error) {
@@ -153,17 +169,7 @@ func buildRawResponse(resp *http.Response) ([]byte, error) {
 	return res, nil
 }
 
-func buildErr(data []byte, err *errs.Failure) {
-	resp, e := errs.ErrorResponse(data)
-	err.SetRuntimeError(e)
-	err.SetApiError(resp.ErrorMsg)
-
-	if resp.Errors != nil {
-		err.SetApiErrors(errs.ErrorsHandler(resp.Errors))
-	}
-}
-
-// checkBy select identifier type
+// checkBy select identifier type.
 func checkBy(by string) string {
 	var context = ByID
 
@@ -174,7 +180,7 @@ func checkBy(by string) string {
 	return context
 }
 
-// fillSite add site code to parameters if present
+// fillSite add site code to parameters if present.
 func fillSite(p *url.Values, site []string) {
 	if len(site) > 0 {
 		s := site[0]
@@ -206,21 +212,16 @@ func fillSite(p *url.Values, site []string) {
 // 	for _, value := range data.versions {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) APIVersions() (VersionResponse, int, *errs.Failure) {
+func (c *Client) APIVersions() (VersionResponse, int, error) {
 	var resp VersionResponse
 
 	data, status, err := c.GetRequest("/api-versions", false)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -245,21 +246,16 @@ func (c *Client) APIVersions() (VersionResponse, int, *errs.Failure) {
 // 	for _, value := range data.credentials {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) APICredentials() (CredentialResponse, int, *errs.Failure) {
+func (c *Client) APICredentials() (CredentialResponse, int, error) {
 	var resp CredentialResponse
 
 	data, status, err := c.GetRequest("/credentials", false)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -289,23 +285,18 @@ func (c *Client) APICredentials() (CredentialResponse, int, *errs.Failure) {
 // 	for _, value := range data.Customers {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) Customers(parameters CustomersRequest) (CustomersResponse, int, *errs.Failure) {
+func (c *Client) Customers(parameters CustomersRequest) (CustomersResponse, int, error) {
 	var resp CustomersResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -326,7 +317,7 @@ func (c *Client) Customers(parameters CustomersRequest) (CustomersResponse, int,
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CustomersCombine(customers []Customer, resultCustomer Customer) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CustomersCombine(customers []Customer, resultCustomer Customer) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	combineJSONIn, _ := json.Marshal(&customers)
@@ -338,17 +329,12 @@ func (c *Client) CustomersCombine(customers []Customer, resultCustomer Customer)
 	}
 
 	data, status, err := c.PostRequest("/customers/combine", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -383,7 +369,7 @@ func (c *Client) CustomersCombine(customers []Customer, resultCustomer Customer)
 //	if data.Success == true {
 //		fmt.Printf("%v", err.Id)
 //	}
-func (c *Client) CustomerCreate(customer Customer, site ...string) (CustomerChangeResponse, int, *errs.Failure) {
+func (c *Client) CustomerCreate(customer Customer, site ...string) (CustomerChangeResponse, int, error) {
 	var resp CustomerChangeResponse
 
 	customerJSON, _ := json.Marshal(&customer)
@@ -395,17 +381,12 @@ func (c *Client) CustomerCreate(customer Customer, site ...string) (CustomerChan
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/customers/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -429,7 +410,7 @@ func (c *Client) CustomerCreate(customer Customer, site ...string) (CustomerChan
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CustomersFixExternalIds(customers []IdentifiersPair) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CustomersFixExternalIds(customers []IdentifiersPair) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	customersJSON, _ := json.Marshal(&customers)
@@ -439,17 +420,12 @@ func (c *Client) CustomersFixExternalIds(customers []IdentifiersPair) (Successfu
 	}
 
 	data, status, err := c.PostRequest("/customers/fix-external-ids", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -478,23 +454,18 @@ func (c *Client) CustomersFixExternalIds(customers []IdentifiersPair) (Successfu
 // 	for _, value := range data.History {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) CustomersHistory(parameters CustomersHistoryRequest) (CustomersHistoryResponse, int, *errs.Failure) {
+func (c *Client) CustomersHistory(parameters CustomersHistoryRequest) (CustomersHistoryResponse, int, error) {
 	var resp CustomersHistoryResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers/history?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -524,23 +495,18 @@ func (c *Client) CustomersHistory(parameters CustomersHistoryRequest) (Customers
 // 	for _, value := range data.Notes {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) CustomerNotes(parameters NotesRequest) (NotesResponse, int, *errs.Failure) {
+func (c *Client) CustomerNotes(parameters NotesRequest) (NotesResponse, int, error) {
 	var resp NotesResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers/notes?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -571,7 +537,7 @@ func (c *Client) CustomerNotes(parameters NotesRequest) (NotesResponse, int, *er
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) CustomerNoteCreate(note Note, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CustomerNoteCreate(note Note, site ...string) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	noteJSON, _ := json.Marshal(&note)
@@ -583,17 +549,12 @@ func (c *Client) CustomerNoteCreate(note Note, site ...string) (CreateResponse,
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/customers/notes/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -613,7 +574,7 @@ func (c *Client) CustomerNoteCreate(note Note, site ...string) (CreateResponse,
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CustomerNoteDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CustomerNoteDelete(id int) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	p := url.Values{
@@ -621,17 +582,12 @@ func (c *Client) CustomerNoteDelete(id int) (SuccessfulResponse, int, *errs.Fail
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers/notes/%d/delete", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -671,7 +627,7 @@ func (c *Client) CustomerNoteDelete(id int) (SuccessfulResponse, int, *errs.Fail
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.UploadedCustomers)
 // 	}
-func (c *Client) CustomersUpload(customers []Customer, site ...string) (CustomersUploadResponse, int, *errs.Failure) {
+func (c *Client) CustomersUpload(customers []Customer, site ...string) (CustomersUploadResponse, int, error) {
 	var resp CustomersUploadResponse
 
 	uploadJSON, _ := json.Marshal(&customers)
@@ -683,17 +639,12 @@ func (c *Client) CustomersUpload(customers []Customer, site ...string) (Customer
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/customers/upload", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -718,7 +669,7 @@ func (c *Client) CustomersUpload(customers []Customer, site ...string) (Customer
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Customer)
 // 	}
-func (c *Client) Customer(id, by, site string) (CustomerResponse, int, *errs.Failure) {
+func (c *Client) Customer(id, by, site string) (CustomerResponse, int, error) {
 	var resp CustomerResponse
 	var context = checkBy(by)
 
@@ -726,17 +677,12 @@ func (c *Client) Customer(id, by, site string) (CustomerResponse, int, *errs.Fai
 	params, _ := query.Values(fw)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers/%s?%s", id, params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -770,7 +716,7 @@ func (c *Client) Customer(id, by, site string) (CustomerResponse, int, *errs.Fai
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Customer)
 // 	}
-func (c *Client) CustomerEdit(customer Customer, by string, site ...string) (CustomerChangeResponse, int, *errs.Failure) {
+func (c *Client) CustomerEdit(customer Customer, by string, site ...string) (CustomerChangeResponse, int, error) {
 	var resp CustomerChangeResponse
 	var uid = strconv.Itoa(customer.ID)
 	var context = checkBy(by)
@@ -789,17 +735,12 @@ func (c *Client) CustomerEdit(customer Customer, by string, site ...string) (Cus
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers/%s/edit", uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -829,23 +770,18 @@ func (c *Client) CustomerEdit(customer Customer, by string, site ...string) (Cus
 // 	for _, value := range data.CustomersCorporate {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) CorporateCustomers(parameters CorporateCustomersRequest) (CorporateCustomersResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomers(parameters CorporateCustomersRequest) (CorporateCustomersResponse, int, error) {
 	var resp CorporateCustomersResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers-corporate?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -872,7 +808,9 @@ func (c *Client) CorporateCustomers(parameters CorporateCustomersRequest) (Corpo
 //	if data.Success == true {
 //		fmt.Printf("%v", err.Id)
 //	}
-func (c *Client) CorporateCustomerCreate(customer CorporateCustomer, site ...string) (CorporateCustomerChangeResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerCreate(customer CorporateCustomer, site ...string) (
+	CorporateCustomerChangeResponse, int, error,
+) {
 	var resp CorporateCustomerChangeResponse
 
 	customerJSON, _ := json.Marshal(&customer)
@@ -884,17 +822,12 @@ func (c *Client) CorporateCustomerCreate(customer CorporateCustomer, site ...str
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/customers-corporate/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -918,7 +851,7 @@ func (c *Client) CorporateCustomerCreate(customer CorporateCustomer, site ...str
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CorporateCustomersFixExternalIds(customers []IdentifiersPair) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomersFixExternalIds(customers []IdentifiersPair) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	customersJSON, _ := json.Marshal(&customers)
@@ -928,17 +861,12 @@ func (c *Client) CorporateCustomersFixExternalIds(customers []IdentifiersPair) (
 	}
 
 	data, status, err := c.PostRequest("/customers-corporate/fix-external-ids", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -967,23 +895,20 @@ func (c *Client) CorporateCustomersFixExternalIds(customers []IdentifiersPair) (
 // 	for _, value := range data.History {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) CorporateCustomersHistory(parameters CorporateCustomersHistoryRequest) (CorporateCustomersHistoryResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomersHistory(parameters CorporateCustomersHistoryRequest) (
+	CorporateCustomersHistoryResponse, int, error,
+) {
 	var resp CorporateCustomersHistoryResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers-corporate/history?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1013,23 +938,20 @@ func (c *Client) CorporateCustomersHistory(parameters CorporateCustomersHistoryR
 // 	for _, value := range data.Notes {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) CorporateCustomersNotes(parameters CorporateCustomersNotesRequest) (CorporateCustomersNotesResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomersNotes(parameters CorporateCustomersNotesRequest) (
+	CorporateCustomersNotesResponse, int, error,
+) {
 	var resp CorporateCustomersNotesResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers-corporate/notes?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1059,7 +981,7 @@ func (c *Client) CorporateCustomersNotes(parameters CorporateCustomersNotesReque
 //	if data.Success == true {
 //		fmt.Printf("%v", err.Id)
 //	}
-func (c *Client) CorporateCustomerNoteCreate(note CorporateCustomerNote, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerNoteCreate(note CorporateCustomerNote, site ...string) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	noteJSON, _ := json.Marshal(&note)
@@ -1071,17 +993,12 @@ func (c *Client) CorporateCustomerNoteCreate(note CorporateCustomerNote, site ..
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/customers-corporate/notes/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1102,7 +1019,7 @@ func (c *Client) CorporateCustomerNoteCreate(note CorporateCustomerNote, site ..
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CorporateCustomerNoteDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerNoteDelete(id int) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	p := url.Values{
@@ -1110,17 +1027,12 @@ func (c *Client) CorporateCustomerNoteDelete(id int) (SuccessfulResponse, int, *
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/notes/%d/delete", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1154,7 +1066,9 @@ func (c *Client) CorporateCustomerNoteDelete(id int) (SuccessfulResponse, int, *
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.UploadedCustomers)
 // 	}
-func (c *Client) CorporateCustomersUpload(customers []CorporateCustomer, site ...string) (CorporateCustomersUploadResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomersUpload(
+	customers []CorporateCustomer, site ...string,
+) (CorporateCustomersUploadResponse, int, error) {
 	var resp CorporateCustomersUploadResponse
 
 	uploadJSON, _ := json.Marshal(&customers)
@@ -1166,17 +1080,12 @@ func (c *Client) CorporateCustomersUpload(customers []CorporateCustomer, site ..
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/customers-corporate/upload", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1201,7 +1110,7 @@ func (c *Client) CorporateCustomersUpload(customers []CorporateCustomer, site ..
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.CorporateCustomer)
 // 	}
-func (c *Client) CorporateCustomer(id, by, site string) (CorporateCustomerResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomer(id, by, site string) (CorporateCustomerResponse, int, error) {
 	var resp CorporateCustomerResponse
 	var context = checkBy(by)
 
@@ -1209,17 +1118,12 @@ func (c *Client) CorporateCustomer(id, by, site string) (CorporateCustomerRespon
 	params, _ := query.Values(fw)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers-corporate/%s?%s", id, params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1252,24 +1156,21 @@ func (c *Client) CorporateCustomer(id, by, site string) (CorporateCustomerRespon
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Addresses)
 // 	}
-func (c *Client) CorporateCustomerAddresses(id string, parameters CorporateCustomerAddressesRequest) (CorporateCustomersAddressesResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerAddresses(
+	id string, parameters CorporateCustomerAddressesRequest,
+) (CorporateCustomersAddressesResponse, int, error) {
 	var resp CorporateCustomersAddressesResponse
 
 	parameters.By = checkBy(parameters.By)
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers-corporate/%s/addresses?%s", id, params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1297,7 +1198,9 @@ func (c *Client) CorporateCustomerAddresses(id string, parameters CorporateCusto
 //	if data.Success == true {
 //		fmt.Printf("%v", data.ID)
 //	}
-func (c *Client) CorporateCustomerAddressesCreate(id string, by string, address CorporateCustomerAddress, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerAddressesCreate(
+	id string, by string, address CorporateCustomerAddress, site ...string,
+) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	addressJSON, _ := json.Marshal(&address)
@@ -1310,17 +1213,12 @@ func (c *Client) CorporateCustomerAddressesCreate(id string, by string, address
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/%s/addresses/create", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1353,7 +1251,9 @@ func (c *Client) CorporateCustomerAddressesCreate(id string, by string, address
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Customer)
 // 	}
-func (c *Client) CorporateCustomerAddressesEdit(customerID, customerBy, entityBy string, address CorporateCustomerAddress, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerAddressesEdit(
+	customerID, customerBy, entityBy string, address CorporateCustomerAddress, site ...string,
+) (CreateResponse, int, error) {
 	var (
 		resp CreateResponse
 		uid  string
@@ -1380,17 +1280,12 @@ func (c *Client) CorporateCustomerAddressesEdit(customerID, customerBy, entityBy
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/%s/addresses/%s/edit", customerID, uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1423,24 +1318,21 @@ func (c *Client) CorporateCustomerAddressesEdit(customerID, customerBy, entityBy
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Companies)
 // 	}
-func (c *Client) CorporateCustomerCompanies(id string, parameters IdentifiersPairRequest) (CorporateCustomerCompaniesResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerCompanies(
+	id string, parameters IdentifiersPairRequest,
+) (CorporateCustomerCompaniesResponse, int, error) {
 	var resp CorporateCustomerCompaniesResponse
 
 	parameters.By = checkBy(parameters.By)
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers-corporate/%s/companies?%s", id, params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1467,7 +1359,9 @@ func (c *Client) CorporateCustomerCompanies(id string, parameters IdentifiersPai
 //	if data.Success == true {
 //		fmt.Printf("%v", data.ID)
 //	}
-func (c *Client) CorporateCustomerCompaniesCreate(id string, by string, company Company, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerCompaniesCreate(
+	id string, by string, company Company, site ...string,
+) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	companyJSON, _ := json.Marshal(&company)
@@ -1480,17 +1374,12 @@ func (c *Client) CorporateCustomerCompaniesCreate(id string, by string, company
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/%s/companies/create", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1523,7 +1412,9 @@ func (c *Client) CorporateCustomerCompaniesCreate(id string, by string, company
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) CorporateCustomerCompaniesEdit(customerID, customerBy, entityBy string, company Company, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerCompaniesEdit(
+	customerID, customerBy, entityBy string, company Company, site ...string,
+) (CreateResponse, int, error) {
 	var (
 		resp CreateResponse
 		uid  string
@@ -1550,17 +1441,12 @@ func (c *Client) CorporateCustomerCompaniesEdit(customerID, customerBy, entityBy
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/%s/companies/%s/edit", customerID, uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1593,24 +1479,21 @@ func (c *Client) CorporateCustomerCompaniesEdit(customerID, customerBy, entityBy
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Contacts)
 // 	}
-func (c *Client) CorporateCustomerContacts(id string, parameters IdentifiersPairRequest) (CorporateCustomerContactsResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerContacts(
+	id string, parameters IdentifiersPairRequest,
+) (CorporateCustomerContactsResponse, int, error) {
 	var resp CorporateCustomerContactsResponse
 
 	parameters.By = checkBy(parameters.By)
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/customers-corporate/%s/contacts?%s", id, params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1642,7 +1525,9 @@ func (c *Client) CorporateCustomerContacts(id string, parameters IdentifiersPair
 //	if data.Success == true {
 //		fmt.Printf("%v", data.ID)
 //	}
-func (c *Client) CorporateCustomerContactsCreate(id string, by string, contact CorporateCustomerContact, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerContactsCreate(
+	id string, by string, contact CorporateCustomerContact, site ...string,
+) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	companyJSON, _ := json.Marshal(&contact)
@@ -1655,17 +1540,12 @@ func (c *Client) CorporateCustomerContactsCreate(id string, by string, contact C
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/%s/contacts/create", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1695,7 +1575,9 @@ func (c *Client) CorporateCustomerContactsCreate(id string, by string, contact C
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) CorporateCustomerContactsEdit(customerID, customerBy, entityBy string, contact CorporateCustomerContact, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerContactsEdit(
+	customerID, customerBy, entityBy string, contact CorporateCustomerContact, site ...string,
+) (CreateResponse, int, error) {
 	var (
 		resp CreateResponse
 		uid  string
@@ -1722,17 +1604,12 @@ func (c *Client) CorporateCustomerContactsEdit(customerID, customerBy, entityBy
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/%s/contacts/%s/edit", customerID, uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1766,7 +1643,9 @@ func (c *Client) CorporateCustomerContactsEdit(customerID, customerBy, entityBy
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Customer)
 // 	}
-func (c *Client) CorporateCustomerEdit(customer CorporateCustomer, by string, site ...string) (CustomerChangeResponse, int, *errs.Failure) {
+func (c *Client) CorporateCustomerEdit(customer CorporateCustomer, by string, site ...string) (
+	CustomerChangeResponse, int, error,
+) {
 	var resp CustomerChangeResponse
 	var uid = strconv.Itoa(customer.ID)
 	var context = checkBy(by)
@@ -1785,17 +1664,12 @@ func (c *Client) CorporateCustomerEdit(customer CorporateCustomer, by string, si
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/customers-corporate/%s/edit", uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1830,7 +1704,9 @@ func (c *Client) CorporateCustomerEdit(customer CorporateCustomer, by string, si
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
 //
-func (c *Client) DeliveryTracking(parameters []DeliveryTrackingRequest, subcode string) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) DeliveryTracking(parameters []DeliveryTrackingRequest, subcode string) (
+	SuccessfulResponse, int, error,
+) {
 	var resp SuccessfulResponse
 
 	updateJSON, _ := json.Marshal(&parameters)
@@ -1840,17 +1716,12 @@ func (c *Client) DeliveryTracking(parameters []DeliveryTrackingRequest, subcode
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/delivery/generic/%s/tracking", subcode), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1880,23 +1751,18 @@ func (c *Client) DeliveryTracking(parameters []DeliveryTrackingRequest, subcode
 // 	for _, value := range data.DeliveryShipments {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) DeliveryShipments(parameters DeliveryShipmentsRequest) (DeliveryShipmentsResponse, int, *errs.Failure) {
+func (c *Client) DeliveryShipments(parameters DeliveryShipmentsRequest) (DeliveryShipmentsResponse, int, error) {
 	var resp DeliveryShipmentsResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/delivery/shipments?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1931,7 +1797,9 @@ func (c *Client) DeliveryShipments(parameters DeliveryShipmentsRequest) (Deliver
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) DeliveryShipmentCreate(shipment DeliveryShipment, deliveryType string, site ...string) (DeliveryShipmentUpdateResponse, int, *errs.Failure) {
+func (c *Client) DeliveryShipmentCreate(
+	shipment DeliveryShipment, deliveryType string, site ...string,
+) (DeliveryShipmentUpdateResponse, int, error) {
 	var resp DeliveryShipmentUpdateResponse
 	updateJSON, _ := json.Marshal(&shipment)
 
@@ -1943,17 +1811,12 @@ func (c *Client) DeliveryShipmentCreate(shipment DeliveryShipment, deliveryType
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/delivery/shipments/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -1978,21 +1841,16 @@ func (c *Client) DeliveryShipmentCreate(shipment DeliveryShipment, deliveryType
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.DeliveryShipment)
 // 	}
-func (c *Client) DeliveryShipment(id int) (DeliveryShipmentResponse, int, *errs.Failure) {
+func (c *Client) DeliveryShipment(id int) (DeliveryShipmentResponse, int, error) {
 	var resp DeliveryShipmentResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/delivery/shipments/%d", id))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2019,7 +1877,9 @@ func (c *Client) DeliveryShipment(id int) (DeliveryShipmentResponse, int, *errs.
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) DeliveryShipmentEdit(shipment DeliveryShipment, site ...string) (DeliveryShipmentUpdateResponse, int, *errs.Failure) {
+func (c *Client) DeliveryShipmentEdit(shipment DeliveryShipment, site ...string) (
+	DeliveryShipmentUpdateResponse, int, error,
+) {
 	var resp DeliveryShipmentUpdateResponse
 	updateJSON, _ := json.Marshal(&shipment)
 
@@ -2030,17 +1890,12 @@ func (c *Client) DeliveryShipmentEdit(shipment DeliveryShipment, site ...string)
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/delivery/shipments/%s/edit", strconv.Itoa(shipment.ID)), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2065,21 +1920,16 @@ func (c *Client) DeliveryShipmentEdit(shipment DeliveryShipment, site ...string)
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.IntegrationModule)
 // 	}
-func (c *Client) IntegrationModule(code string) (IntegrationModuleResponse, int, *errs.Failure) {
+func (c *Client) IntegrationModule(code string) (IntegrationModuleResponse, int, error) {
 	var resp IntegrationModuleResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/integration-modules/%s", code))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2116,24 +1966,21 @@ func (c *Client) IntegrationModule(code string) (IntegrationModuleResponse, int,
 //	if data.Success == true {
 //		fmt.Printf("%v\n", data.Info)
 //	}
-func (c *Client) IntegrationModuleEdit(integrationModule IntegrationModule) (IntegrationModuleEditResponse, int, *errs.Failure) {
+func (c *Client) IntegrationModuleEdit(integrationModule IntegrationModule) (
+	IntegrationModuleEditResponse, int, error,
+) {
 	var resp IntegrationModuleEditResponse
 	updateJSON, _ := json.Marshal(&integrationModule)
 
 	p := url.Values{"integrationModule": {string(updateJSON[:])}}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/integration-modules/%s/edit", integrationModule.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2158,23 +2005,18 @@ func (c *Client) IntegrationModuleEdit(integrationModule IntegrationModule) (Int
 // 	for _, value := range data.Orders {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) Orders(parameters OrdersRequest) (OrdersResponse, int, *errs.Failure) {
+func (c *Client) Orders(parameters OrdersRequest) (OrdersResponse, int, error) {
 	var resp OrdersResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/orders?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2195,7 +2037,7 @@ func (c *Client) Orders(parameters OrdersRequest) (OrdersResponse, int, *errs.Fa
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) OrdersCombine(technique string, order, resultOrder Order) (OperationResponse, int, *errs.Failure) {
+func (c *Client) OrdersCombine(technique string, order, resultOrder Order) (OperationResponse, int, error) {
 	var resp OperationResponse
 
 	combineJSONIn, _ := json.Marshal(&order)
@@ -2208,17 +2050,12 @@ func (c *Client) OrdersCombine(technique string, order, resultOrder Order) (Oper
 	}
 
 	data, status, err := c.PostRequest("/orders/combine", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2249,7 +2086,7 @@ func (c *Client) OrdersCombine(technique string, order, resultOrder Order) (Oper
 // 	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) OrderCreate(order Order, site ...string) (OrderCreateResponse, int, *errs.Failure) {
+func (c *Client) OrderCreate(order Order, site ...string) (OrderCreateResponse, int, error) {
 	var resp OrderCreateResponse
 	orderJSON, _ := json.Marshal(&order)
 
@@ -2260,17 +2097,12 @@ func (c *Client) OrderCreate(order Order, site ...string) (OrderCreateResponse,
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/orders/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2298,7 +2130,7 @@ func (c *Client) OrderCreate(order Order, site ...string) (OrderCreateResponse,
 //	if data.Success == true {
 //		fmt.Printf("%v\n", data.ID)
 //	}
-func (c *Client) OrdersFixExternalIds(orders []IdentifiersPair) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) OrdersFixExternalIds(orders []IdentifiersPair) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	ordersJSON, _ := json.Marshal(&orders)
@@ -2308,17 +2140,12 @@ func (c *Client) OrdersFixExternalIds(orders []IdentifiersPair) (SuccessfulRespo
 	}
 
 	data, status, err := c.PostRequest("/orders/fix-external-ids", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2343,23 +2170,18 @@ func (c *Client) OrdersFixExternalIds(orders []IdentifiersPair) (SuccessfulRespo
 // 	for _, value := range data.History {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) OrdersHistory(parameters OrdersHistoryRequest) (OrdersHistoryResponse, int, *errs.Failure) {
+func (c *Client) OrdersHistory(parameters OrdersHistoryRequest) (OrdersHistoryResponse, int, error) {
 	var resp OrdersHistoryResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/orders/history?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2390,7 +2212,7 @@ func (c *Client) OrdersHistory(parameters OrdersHistoryRequest) (OrdersHistoryRe
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) OrderPaymentCreate(payment Payment, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) OrderPaymentCreate(payment Payment, site ...string) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	paymentJSON, _ := json.Marshal(&payment)
@@ -2402,17 +2224,12 @@ func (c *Client) OrderPaymentCreate(payment Payment, site ...string) (CreateResp
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/orders/payments/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2433,7 +2250,7 @@ func (c *Client) OrderPaymentCreate(payment Payment, site ...string) (CreateResp
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) OrderPaymentDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) OrderPaymentDelete(id int) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	p := url.Values{
@@ -2441,17 +2258,12 @@ func (c *Client) OrderPaymentDelete(id int) (SuccessfulResponse, int, *errs.Fail
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/orders/payments/%d/delete", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2478,7 +2290,7 @@ func (c *Client) OrderPaymentDelete(id int) (SuccessfulResponse, int, *errs.Fail
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) OrderPaymentEdit(payment Payment, by string, site ...string) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) OrderPaymentEdit(payment Payment, by string, site ...string) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 	var uid = strconv.Itoa(payment.ID)
 	var context = checkBy(by)
@@ -2497,17 +2309,12 @@ func (c *Client) OrderPaymentEdit(payment Payment, by string, site ...string) (S
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/orders/payments/%s/edit", uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2531,23 +2338,18 @@ func (c *Client) OrderPaymentEdit(payment Payment, by string, site ...string) (S
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) OrdersStatuses(request OrdersStatusesRequest) (OrdersStatusesResponse, int, *errs.Failure) {
+func (c *Client) OrdersStatuses(request OrdersStatusesRequest) (OrdersStatusesResponse, int, error) {
 	var resp OrdersStatusesResponse
 
 	params, _ := query.Values(request)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/orders/statuses?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2587,7 +2389,7 @@ func (c *Client) OrdersStatuses(request OrdersStatusesRequest) (OrdersStatusesRe
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.UploadedOrders)
 // 	}
-func (c *Client) OrdersUpload(orders []Order, site ...string) (OrdersUploadResponse, int, *errs.Failure) {
+func (c *Client) OrdersUpload(orders []Order, site ...string) (OrdersUploadResponse, int, error) {
 	var resp OrdersUploadResponse
 
 	uploadJSON, _ := json.Marshal(&orders)
@@ -2599,17 +2401,12 @@ func (c *Client) OrdersUpload(orders []Order, site ...string) (OrdersUploadRespo
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/orders/upload", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2634,7 +2431,7 @@ func (c *Client) OrdersUpload(orders []Order, site ...string) (OrdersUploadRespo
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Order)
 // 	}
-func (c *Client) Order(id, by, site string) (OrderResponse, int, *errs.Failure) {
+func (c *Client) Order(id, by, site string) (OrderResponse, int, error) {
 	var resp OrderResponse
 	var context = checkBy(by)
 
@@ -2642,17 +2439,12 @@ func (c *Client) Order(id, by, site string) (OrderResponse, int, *errs.Failure)
 	params, _ := query.Values(fw)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/orders/%s?%s", id, params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2679,7 +2471,7 @@ func (c *Client) Order(id, by, site string) (OrderResponse, int, *errs.Failure)
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) OrderEdit(order Order, by string, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) OrderEdit(order Order, by string, site ...string) (CreateResponse, int, error) {
 	var resp CreateResponse
 	var uid = strconv.Itoa(order.ID)
 	var context = checkBy(by)
@@ -2698,17 +2490,12 @@ func (c *Client) OrderEdit(order Order, by string, site ...string) (CreateRespon
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/orders/%s/edit", uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2733,23 +2520,18 @@ func (c *Client) OrderEdit(order Order, by string, site ...string) (CreateRespon
 //	for _, value := range data.Packs {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) Packs(parameters PacksRequest) (PacksResponse, int, *errs.Failure) {
+func (c *Client) Packs(parameters PacksRequest) (PacksResponse, int, error) {
 	var resp PacksResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/orders/packs?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2778,7 +2560,7 @@ func (c *Client) Packs(parameters PacksRequest) (PacksResponse, int, *errs.Failu
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) PackCreate(pack Pack) (CreateResponse, int, *errs.Failure) {
+func (c *Client) PackCreate(pack Pack) (CreateResponse, int, error) {
 	var resp CreateResponse
 	packJSON, _ := json.Marshal(&pack)
 
@@ -2787,17 +2569,12 @@ func (c *Client) PackCreate(pack Pack) (CreateResponse, int, *errs.Failure) {
 	}
 
 	data, status, err := c.PostRequest("/orders/packs/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2822,23 +2599,18 @@ func (c *Client) PackCreate(pack Pack) (CreateResponse, int, *errs.Failure) {
 //	for _, value := range data.History {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) PacksHistory(parameters PacksHistoryRequest) (PacksHistoryResponse, int, *errs.Failure) {
+func (c *Client) PacksHistory(parameters PacksHistoryRequest) (PacksHistoryResponse, int, error) {
 	var resp PacksHistoryResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/orders/packs/history?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2863,21 +2635,16 @@ func (c *Client) PacksHistory(parameters PacksHistoryRequest) (PacksHistoryRespo
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Pack)
 // 	}
-func (c *Client) Pack(id int) (PackResponse, int, *errs.Failure) {
+func (c *Client) Pack(id int) (PackResponse, int, error) {
 	var resp PackResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/orders/packs/%d", id))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2898,21 +2665,16 @@ func (c *Client) Pack(id int) (PackResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) PackDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) PackDelete(id int) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/orders/packs/%d/delete", id), url.Values{})
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -2933,7 +2695,7 @@ func (c *Client) PackDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) PackEdit(pack Pack) (CreateResponse, int, *errs.Failure) {
+func (c *Client) PackEdit(pack Pack) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	packJSON, _ := json.Marshal(&pack)
@@ -2943,59 +2705,44 @@ func (c *Client) PackEdit(pack Pack) (CreateResponse, int, *errs.Failure) {
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/orders/packs/%d/edit", pack.ID), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // Countries returns list of available country codes
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-countries
-func (c *Client) Countries() (CountriesResponse, int, *errs.Failure) {
+func (c *Client) Countries() (CountriesResponse, int, error) {
 	var resp CountriesResponse
 
 	data, status, err := c.GetRequest("/reference/countries")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // CostGroups returns costs groups list
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-cost-groups
-func (c *Client) CostGroups() (CostGroupsResponse, int, *errs.Failure) {
+func (c *Client) CostGroups() (CostGroupsResponse, int, error) {
 	var resp CostGroupsResponse
 
 	data, status, err := c.GetRequest("/reference/cost-groups")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3019,7 +2766,7 @@ func (c *Client) CostGroups() (CostGroupsResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CostGroupEdit(costGroup CostGroup) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CostGroupEdit(costGroup CostGroup) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&costGroup)
@@ -3029,38 +2776,28 @@ func (c *Client) CostGroupEdit(costGroup CostGroup) (SuccessfulResponse, int, *e
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/cost-groups/%s/edit", costGroup.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // CostItems returns costs items list
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-cost-items
-func (c *Client) CostItems() (CostItemsResponse, int, *errs.Failure) {
+func (c *Client) CostItems() (CostItemsResponse, int, error) {
 	var resp CostItemsResponse
 
 	data, status, err := c.GetRequest("/reference/cost-items")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3084,7 +2821,7 @@ func (c *Client) CostItems() (CostItemsResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CostItemEdit(costItem CostItem) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CostItemEdit(costItem CostItem) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&costItem)
@@ -3094,38 +2831,28 @@ func (c *Client) CostItemEdit(costItem CostItem) (SuccessfulResponse, int, *errs
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/cost-items/%s/edit", costItem.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // Couriers returns list of couriers
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-couriers
-func (c *Client) Couriers() (CouriersResponse, int, *errs.Failure) {
+func (c *Client) Couriers() (CouriersResponse, int, error) {
 	var resp CouriersResponse
 
 	data, status, err := c.GetRequest("/reference/couriers")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3155,7 +2882,7 @@ func (c *Client) Couriers() (CouriersResponse, int, *errs.Failure) {
 // 	if data.Success == true {
 // 		fmt.Printf("%v", data.ID)
 // 	}
-func (c *Client) CourierCreate(courier Courier) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CourierCreate(courier Courier) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	objJSON, _ := json.Marshal(&courier)
@@ -3165,17 +2892,12 @@ func (c *Client) CourierCreate(courier Courier) (CreateResponse, int, *errs.Fail
 	}
 
 	data, status, err := c.PostRequest("/reference/couriers/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3199,7 +2921,7 @@ func (c *Client) CourierCreate(courier Courier) (CreateResponse, int, *errs.Fail
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CourierEdit(courier Courier) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CourierEdit(courier Courier) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&courier)
@@ -3209,38 +2931,28 @@ func (c *Client) CourierEdit(courier Courier) (SuccessfulResponse, int, *errs.Fa
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/couriers/%d/edit", courier.ID), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // DeliveryServices returns list of delivery services
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-delivery-services
-func (c *Client) DeliveryServices() (DeliveryServiceResponse, int, *errs.Failure) {
+func (c *Client) DeliveryServices() (DeliveryServiceResponse, int, error) {
 	var resp DeliveryServiceResponse
 
 	data, status, err := c.GetRequest("/reference/delivery-services")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3264,7 +2976,7 @@ func (c *Client) DeliveryServices() (DeliveryServiceResponse, int, *errs.Failure
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) DeliveryServiceEdit(deliveryService DeliveryService) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) DeliveryServiceEdit(deliveryService DeliveryService) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&deliveryService)
@@ -3274,38 +2986,28 @@ func (c *Client) DeliveryServiceEdit(deliveryService DeliveryService) (Successfu
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/delivery-services/%s/edit", deliveryService.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // DeliveryTypes returns list of delivery types
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-delivery-types
-func (c *Client) DeliveryTypes() (DeliveryTypesResponse, int, *errs.Failure) {
+func (c *Client) DeliveryTypes() (DeliveryTypesResponse, int, error) {
 	var resp DeliveryTypesResponse
 
 	data, status, err := c.GetRequest("/reference/delivery-types")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3331,7 +3033,7 @@ func (c *Client) DeliveryTypes() (DeliveryTypesResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) DeliveryTypeEdit(deliveryType DeliveryType) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) DeliveryTypeEdit(deliveryType DeliveryType) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&deliveryType)
@@ -3341,38 +3043,28 @@ func (c *Client) DeliveryTypeEdit(deliveryType DeliveryType) (SuccessfulResponse
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/delivery-types/%s/edit", deliveryType.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // LegalEntities returns list of legal entities
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-legal-entities
-func (c *Client) LegalEntities() (LegalEntitiesResponse, int, *errs.Failure) {
+func (c *Client) LegalEntities() (LegalEntitiesResponse, int, error) {
 	var resp LegalEntitiesResponse
 
 	data, status, err := c.GetRequest("/reference/legal-entities")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3396,7 +3088,7 @@ func (c *Client) LegalEntities() (LegalEntitiesResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) LegalEntityEdit(legalEntity LegalEntity) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) LegalEntityEdit(legalEntity LegalEntity) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&legalEntity)
@@ -3406,38 +3098,28 @@ func (c *Client) LegalEntityEdit(legalEntity LegalEntity) (SuccessfulResponse, i
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/legal-entities/%s/edit", legalEntity.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // OrderMethods returns list of order methods
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-order-methods
-func (c *Client) OrderMethods() (OrderMethodsResponse, int, *errs.Failure) {
+func (c *Client) OrderMethods() (OrderMethodsResponse, int, error) {
 	var resp OrderMethodsResponse
 
 	data, status, err := c.GetRequest("/reference/order-methods")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3462,7 +3144,7 @@ func (c *Client) OrderMethods() (OrderMethodsResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) OrderMethodEdit(orderMethod OrderMethod) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) OrderMethodEdit(orderMethod OrderMethod) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&orderMethod)
@@ -3472,38 +3154,28 @@ func (c *Client) OrderMethodEdit(orderMethod OrderMethod) (SuccessfulResponse, i
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/order-methods/%s/edit", orderMethod.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // OrderTypes return list of order types
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-order-types
-func (c *Client) OrderTypes() (OrderTypesResponse, int, *errs.Failure) {
+func (c *Client) OrderTypes() (OrderTypesResponse, int, error) {
 	var resp OrderTypesResponse
 
 	data, status, err := c.GetRequest("/reference/order-types")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3528,7 +3200,7 @@ func (c *Client) OrderTypes() (OrderTypesResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) OrderTypeEdit(orderType OrderType) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) OrderTypeEdit(orderType OrderType) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&orderType)
@@ -3538,45 +3210,35 @@ func (c *Client) OrderTypeEdit(orderType OrderType) (SuccessfulResponse, int, *e
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/order-types/%s/edit", orderType.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // PaymentStatuses returns list of payment statuses
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-payment-statuses
-func (c *Client) PaymentStatuses() (PaymentStatusesResponse, int, *errs.Failure) {
+func (c *Client) PaymentStatuses() (PaymentStatusesResponse, int, error) {
 	var resp PaymentStatusesResponse
 
 	data, status, err := c.GetRequest("/reference/payment-statuses")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // PaymentStatusEdit payment status creation/editing
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-payment-statuses-code-edit
-func (c *Client) PaymentStatusEdit(paymentStatus PaymentStatus) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) PaymentStatusEdit(paymentStatus PaymentStatus) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&paymentStatus)
@@ -3586,45 +3248,35 @@ func (c *Client) PaymentStatusEdit(paymentStatus PaymentStatus) (SuccessfulRespo
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/payment-statuses/%s/edit", paymentStatus.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // PaymentTypes returns list of payment types
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-payment-types
-func (c *Client) PaymentTypes() (PaymentTypesResponse, int, *errs.Failure) {
+func (c *Client) PaymentTypes() (PaymentTypesResponse, int, error) {
 	var resp PaymentTypesResponse
 
 	data, status, err := c.GetRequest("/reference/payment-types")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // PaymentTypeEdit payment type create/edit
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-payment-types-code-edit
-func (c *Client) PaymentTypeEdit(paymentType PaymentType) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) PaymentTypeEdit(paymentType PaymentType) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&paymentType)
@@ -3634,45 +3286,35 @@ func (c *Client) PaymentTypeEdit(paymentType PaymentType) (SuccessfulResponse, i
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/payment-types/%s/edit", paymentType.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // PriceTypes returns list of price types
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-price-types
-func (c *Client) PriceTypes() (PriceTypesResponse, int, *errs.Failure) {
+func (c *Client) PriceTypes() (PriceTypesResponse, int, error) {
 	var resp PriceTypesResponse
 
 	data, status, err := c.GetRequest("/reference/price-types")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // PriceTypeEdit price type create/edit
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-price-types-code-edit
-func (c *Client) PriceTypeEdit(priceType PriceType) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) PriceTypeEdit(priceType PriceType) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&priceType)
@@ -3682,45 +3324,35 @@ func (c *Client) PriceTypeEdit(priceType PriceType) (SuccessfulResponse, int, *e
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/price-types/%s/edit", priceType.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // ProductStatuses returns list of item statuses in order
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-product-statuses
-func (c *Client) ProductStatuses() (ProductStatusesResponse, int, *errs.Failure) {
+func (c *Client) ProductStatuses() (ProductStatusesResponse, int, error) {
 	var resp ProductStatusesResponse
 
 	data, status, err := c.GetRequest("/reference/product-statuses")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // ProductStatusEdit order item status create/edit
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-product-statuses-code-edit
-func (c *Client) ProductStatusEdit(productStatus ProductStatus) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) ProductStatusEdit(productStatus ProductStatus) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&productStatus)
@@ -3730,45 +3362,35 @@ func (c *Client) ProductStatusEdit(productStatus ProductStatus) (SuccessfulRespo
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/product-statuses/%s/edit", productStatus.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // Sites returns the sites list
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-sites
-func (c *Client) Sites() (SitesResponse, int, *errs.Failure) {
+func (c *Client) Sites() (SitesResponse, int, error) {
 	var resp SitesResponse
 
 	data, status, err := c.GetRequest("/reference/sites")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // SiteEdit site create/edit
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-sites-code-edit
-func (c *Client) SiteEdit(site Site) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) SiteEdit(site Site) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&site)
@@ -3778,66 +3400,51 @@ func (c *Client) SiteEdit(site Site) (SuccessfulResponse, int, *errs.Failure) {
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/sites/%s/edit", site.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // StatusGroups returns list of order status groups
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-status-groups
-func (c *Client) StatusGroups() (StatusGroupsResponse, int, *errs.Failure) {
+func (c *Client) StatusGroups() (StatusGroupsResponse, int, error) {
 	var resp StatusGroupsResponse
 
 	data, status, err := c.GetRequest("/reference/status-groups")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // Statuses returns list of order statuses
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-statuses
-func (c *Client) Statuses() (StatusesResponse, int, *errs.Failure) {
+func (c *Client) Statuses() (StatusesResponse, int, error) {
 	var resp StatusesResponse
 
 	data, status, err := c.GetRequest("/reference/statuses")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // StatusEdit order status create/edit
 //
-// For more information see www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-sites-code-edit
-func (c *Client) StatusEdit(st Status) (SuccessfulResponse, int, *errs.Failure) {
+// For more information see www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-sites-code-edit.
+func (c *Client) StatusEdit(st Status) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&st)
@@ -3847,45 +3454,35 @@ func (c *Client) StatusEdit(st Status) (SuccessfulResponse, int, *errs.Failure)
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/statuses/%s/edit", st.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // Stores returns list of warehouses
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-stores
-func (c *Client) Stores() (StoresResponse, int, *errs.Failure) {
+func (c *Client) Stores() (StoresResponse, int, error) {
 	var resp StoresResponse
 
 	data, status, err := c.GetRequest("/reference/stores")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // StoreEdit warehouse create/edit
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-stores-code-edit
-func (c *Client) StoreEdit(store Store) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) StoreEdit(store Store) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&store)
@@ -3895,45 +3492,35 @@ func (c *Client) StoreEdit(store Store) (SuccessfulResponse, int, *errs.Failure)
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/stores/%s/edit", store.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // Units returns units list
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-reference-units
-func (c *Client) Units() (UnitsResponse, int, *errs.Failure) {
+func (c *Client) Units() (UnitsResponse, int, error) {
 	var resp UnitsResponse
 
 	data, status, err := c.GetRequest("/reference/units")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
 // UnitEdit unit create/edit
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#post--api-v5-reference-units-code-edit
-func (c *Client) UnitEdit(unit Unit) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) UnitEdit(unit Unit) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	objJSON, _ := json.Marshal(&unit)
@@ -3943,17 +3530,12 @@ func (c *Client) UnitEdit(unit Unit) (SuccessfulResponse, int, *errs.Failure) {
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/reference/units/%s/edit", unit.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -3982,23 +3564,18 @@ func (c *Client) UnitEdit(unit Unit) (SuccessfulResponse, int, *errs.Failure) {
 //	for _, value := range data.Segments {
 //		fmt.Printf("%v\n", value)
 //	}
-func (c *Client) Segments(parameters SegmentsRequest) (SegmentsResponse, int, *errs.Failure) {
+func (c *Client) Segments(parameters SegmentsRequest) (SegmentsResponse, int, error) {
 	var resp SegmentsResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/segments?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4021,21 +3598,16 @@ func (c *Client) Segments(parameters SegmentsRequest) (SegmentsResponse, int, *e
 //	}
 //
 //	fmt.Printf("%#v\n", data)
-func (c *Client) Settings() (SettingsResponse, int, *errs.Failure) {
+func (c *Client) Settings() (SettingsResponse, int, error) {
 	var resp SettingsResponse
 
 	data, status, err := c.GetRequest("/settings")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4060,23 +3632,18 @@ func (c *Client) Settings() (SettingsResponse, int, *errs.Failure) {
 //	for _, value := range data.Offers {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) Inventories(parameters InventoriesRequest) (InventoriesResponse, int, *errs.Failure) {
+func (c *Client) Inventories(parameters InventoriesRequest) (InventoriesResponse, int, error) {
 	var resp InventoriesResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/store/inventories?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4118,7 +3685,7 @@ func (c *Client) Inventories(parameters InventoriesRequest) (InventoriesResponse
 //	}
 //
 //	fmt.Printf("%v\n", data.NotFoundOffers)
-func (c *Client) InventoriesUpload(inventories []InventoryUpload, site ...string) (StoreUploadResponse, int, *errs.Failure) {
+func (c *Client) InventoriesUpload(inventories []InventoryUpload, site ...string) (StoreUploadResponse, int, error) {
 	var resp StoreUploadResponse
 
 	uploadJSON, _ := json.Marshal(&inventories)
@@ -4130,17 +3697,12 @@ func (c *Client) InventoriesUpload(inventories []InventoryUpload, site ...string
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/store/inventories/upload", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4174,7 +3736,7 @@ func (c *Client) InventoriesUpload(inventories []InventoryUpload, site ...string
 //	}
 //
 //	fmt.Printf("%v\n", data.NotFoundOffers)
-func (c *Client) PricesUpload(prices []OfferPriceUpload) (StoreUploadResponse, int, *errs.Failure) {
+func (c *Client) PricesUpload(prices []OfferPriceUpload) (StoreUploadResponse, int, error) {
 	var resp StoreUploadResponse
 
 	uploadJSON, _ := json.Marshal(&prices)
@@ -4184,17 +3746,12 @@ func (c *Client) PricesUpload(prices []OfferPriceUpload) (StoreUploadResponse, i
 	}
 
 	data, status, err := c.PostRequest("/store/prices/upload", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4223,23 +3780,18 @@ func (c *Client) PricesUpload(prices []OfferPriceUpload) (StoreUploadResponse, i
 //	for _, value := range data.ProductGroup {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) ProductsGroup(parameters ProductsGroupsRequest) (ProductsGroupsResponse, int, *errs.Failure) {
+func (c *Client) ProductsGroup(parameters ProductsGroupsRequest) (ProductsGroupsResponse, int, error) {
 	var resp ProductsGroupsResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/store/product-groups?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4269,23 +3821,18 @@ func (c *Client) ProductsGroup(parameters ProductsGroupsRequest) (ProductsGroups
 //	for _, value := range data.Products {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) Products(parameters ProductsRequest) (ProductsResponse, int, *errs.Failure) {
+func (c *Client) Products(parameters ProductsRequest) (ProductsResponse, int, error) {
 	var resp ProductsResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/store/products?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4314,23 +3861,18 @@ func (c *Client) Products(parameters ProductsRequest) (ProductsResponse, int, *e
 //	for _, value := range data.Properties {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) ProductsProperties(parameters ProductsPropertiesRequest) (ProductsPropertiesResponse, int, *errs.Failure) {
+func (c *Client) ProductsProperties(parameters ProductsPropertiesRequest) (ProductsPropertiesResponse, int, error) {
 	var resp ProductsPropertiesResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/store/products/properties?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4359,23 +3901,18 @@ func (c *Client) ProductsProperties(parameters ProductsPropertiesRequest) (Produ
 //	for _, value := range data.Tasks {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) Tasks(parameters TasksRequest) (TasksResponse, int, *errs.Failure) {
+func (c *Client) Tasks(parameters TasksRequest) (TasksResponse, int, error) {
 	var resp TasksResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/tasks?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4403,7 +3940,7 @@ func (c *Client) Tasks(parameters TasksRequest) (TasksResponse, int, *errs.Failu
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.ID)
 // 	}
-func (c *Client) TaskCreate(task Task, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) TaskCreate(task Task, site ...string) (CreateResponse, int, error) {
 	var resp CreateResponse
 	taskJSON, _ := json.Marshal(&task)
 
@@ -4414,17 +3951,12 @@ func (c *Client) TaskCreate(task Task, site ...string) (CreateResponse, int, *er
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/tasks/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4449,21 +3981,16 @@ func (c *Client) TaskCreate(task Task, site ...string) (CreateResponse, int, *er
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.Task)
 // 	}
-func (c *Client) Task(id int) (TaskResponse, int, *errs.Failure) {
+func (c *Client) Task(id int) (TaskResponse, int, error) {
 	var resp TaskResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/tasks/%d", id))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4487,7 +4014,7 @@ func (c *Client) Task(id int) (TaskResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) TaskEdit(task Task, site ...string) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) TaskEdit(task Task, site ...string) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 	var uid = strconv.Itoa(task.ID)
 
@@ -4500,15 +4027,15 @@ func (c *Client) TaskEdit(task Task, site ...string) (SuccessfulResponse, int, *
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/tasks/%s/edit", uid), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
 	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
+		a := NewAPIError(data)
+		return resp, status, a
 	}
 
 	return resp, status, nil
@@ -4535,23 +4062,18 @@ func (c *Client) TaskEdit(task Task, site ...string) (SuccessfulResponse, int, *
 //	for _, value := range data.Groups {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) UserGroups(parameters UserGroupsRequest) (UserGroupsResponse, int, *errs.Failure) {
+func (c *Client) UserGroups(parameters UserGroupsRequest) (UserGroupsResponse, int, error) {
 	var resp UserGroupsResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/user-groups?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4576,23 +4098,18 @@ func (c *Client) UserGroups(parameters UserGroupsRequest) (UserGroupsResponse, i
 //	for _, value := range data.Users {
 // 		fmt.Printf("%v\n", value)
 // 	}
-func (c *Client) Users(parameters UsersRequest) (UsersResponse, int, *errs.Failure) {
+func (c *Client) Users(parameters UsersRequest) (UsersResponse, int, error) {
 	var resp UsersResponse
 
 	params, _ := query.Values(parameters)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/users?%s", params.Encode()))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4617,21 +4134,16 @@ func (c *Client) Users(parameters UsersRequest) (UsersResponse, int, *errs.Failu
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.User)
 // 	}
-func (c *Client) User(id int) (UserResponse, int, *errs.Failure) {
+func (c *Client) User(id int) (UserResponse, int, error) {
 	var resp UserResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/users/%d", id))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4652,7 +4164,7 @@ func (c *Client) User(id int) (UserResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) UserStatus(id int, status string) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) UserStatus(id int, status string) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	p := url.Values{
@@ -4660,15 +4172,14 @@ func (c *Client) UserStatus(id int, status string) (SuccessfulResponse, int, *er
 	}
 
 	data, st, err := c.PostRequest(fmt.Sprintf("/users/%d/status", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, st, err
 	}
 
 	json.Unmarshal(data, &resp)
 
 	if resp.Success == false {
-		buildErr(data, err)
-		return resp, st, err
+		return resp, st, NewAPIError(data)
 	}
 
 	return resp, st, nil
@@ -4677,21 +4188,16 @@ func (c *Client) UserStatus(id int, status string) (SuccessfulResponse, int, *er
 // StaticticsUpdate updates statistics
 //
 // For more information see http://www.retailcrm.pro/docs/Developers/ApiVersion5#get--api-v5-statistic-update
-func (c *Client) StaticticsUpdate() (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) StaticticsUpdate() (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	data, status, err := c.GetRequest("/statistic/update")
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4721,24 +4227,19 @@ func (c *Client) StaticticsUpdate() (SuccessfulResponse, int, *errs.Failure) {
 // 	for _, value := range data.Costs {
 // 		fmt.Printf("%v\n", value.Summ)
 // 	}
-func (c *Client) Costs(costs CostsRequest) (CostsResponse, int, *errs.Failure) {
+func (c *Client) Costs(costs CostsRequest) (CostsResponse, int, error) {
 	var resp CostsResponse
 
 	params, _ := query.Values(costs)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/costs?%s", params.Encode()))
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4775,7 +4276,7 @@ func (c *Client) Costs(costs CostsRequest) (CostsResponse, int, *errs.Failure) {
 // 	If data.Success == true {
 // 		fmt.Printf("%v", data.ID)
 // 	}
-func (c *Client) CostCreate(cost CostRecord, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CostCreate(cost CostRecord, site ...string) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	costJSON, _ := json.Marshal(&cost)
@@ -4787,17 +4288,12 @@ func (c *Client) CostCreate(cost CostRecord, site ...string) (CreateResponse, in
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest("/costs/create", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4822,7 +4318,7 @@ func (c *Client) CostCreate(cost CostRecord, site ...string) (CreateResponse, in
 // 	If data.Success == true {
 // 		fmt.Printf("Not removed costs: %v", data.NotRemovedIds)
 // 	}
-func (c *Client) CostsDelete(ids []int) (CostsDeleteResponse, int, *errs.Failure) {
+func (c *Client) CostsDelete(ids []int) (CostsDeleteResponse, int, error) {
 	var resp CostsDeleteResponse
 
 	costJSON, _ := json.Marshal(&ids)
@@ -4832,17 +4328,12 @@ func (c *Client) CostsDelete(ids []int) (CostsDeleteResponse, int, *errs.Failure
 	}
 
 	data, status, err := c.PostRequest("/costs/delete", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4884,7 +4375,7 @@ func (c *Client) CostsDelete(ids []int) (CostsDeleteResponse, int, *errs.Failure
 // 	If data.Success == true {
 // 		fmt.Printf("Uploaded costs: %v", data.UploadedCosts)
 // 	}
-func (c *Client) CostsUpload(cost []CostRecord) (CostsUploadResponse, int, *errs.Failure) {
+func (c *Client) CostsUpload(cost []CostRecord) (CostsUploadResponse, int, error) {
 	var resp CostsUploadResponse
 
 	costJSON, _ := json.Marshal(&cost)
@@ -4894,17 +4385,12 @@ func (c *Client) CostsUpload(cost []CostRecord) (CostsUploadResponse, int, *errs
 	}
 
 	data, status, err := c.PostRequest("/costs/upload", p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4929,22 +4415,17 @@ func (c *Client) CostsUpload(cost []CostRecord) (CostsUploadResponse, int, *errs
 // 	If data.Success == true {
 // 		fmt.Printf("%v", data.Cost)
 // 	}
-func (c *Client) Cost(id int) (CostResponse, int, *errs.Failure) {
+func (c *Client) Cost(id int) (CostResponse, int, error) {
 	var resp CostResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/costs/%d", id))
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -4965,7 +4446,7 @@ func (c *Client) Cost(id int) (CostResponse, int, *errs.Failure) {
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) CostDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) CostDelete(id int) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	costJSON, _ := json.Marshal(&id)
@@ -4976,17 +4457,12 @@ func (c *Client) CostDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/costs/%d/delete", id), p)
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5016,7 +4492,7 @@ func (c *Client) CostDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
 // 	If data.Success == true {
 // 		fmt.Printf("%v", data.Id)
 // 	}
-func (c *Client) CostEdit(id int, cost CostRecord, site ...string) (CreateResponse, int, *errs.Failure) {
+func (c *Client) CostEdit(id int, cost CostRecord, site ...string) (CreateResponse, int, error) {
 	var resp CreateResponse
 
 	costJSON, _ := json.Marshal(&cost)
@@ -5028,17 +4504,12 @@ func (c *Client) CostEdit(id int, cost CostRecord, site ...string) (CreateRespon
 	fillSite(&p, site)
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/costs/%d/edit", id), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5063,7 +4534,7 @@ func (c *Client) CostEdit(id int, cost CostRecord, site ...string) (CreateRespon
 // 	if status >= http.StatusBadRequest {
 // 		fmt.Printf("%v", err.ApiError())
 // 	}
-func (c *Client) Files(files FilesRequest) (FilesResponse, int, *errs.Failure) {
+func (c *Client) Files(files FilesRequest) (FilesResponse, int, error) {
 	var resp FilesResponse
 
 	params, _ := query.Values(files)
@@ -5076,11 +4547,6 @@ func (c *Client) Files(files FilesRequest) (FilesResponse, int, *errs.Failure) {
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5106,7 +4572,7 @@ func (c *Client) Files(files FilesRequest) (FilesResponse, int, *errs.Failure) {
 //  if status >= http.StatusBadRequest {
 // 	    fmt.Printf("%v", err.Error())
 //  }
-func (c *Client) FileUpload(reader io.Reader) (FileUploadResponse, int, *errs.Failure) {
+func (c *Client) FileUpload(reader io.Reader) (FileUploadResponse, int, error) {
 	var resp FileUploadResponse
 
 	data, status, err := c.PostRequest("/files/upload", reader, "application/octet-stream")
@@ -5117,11 +4583,6 @@ func (c *Client) FileUpload(reader io.Reader) (FileUploadResponse, int, *errs.Fa
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5146,21 +4607,16 @@ func (c *Client) FileUpload(reader io.Reader) (FileUploadResponse, int, *errs.Fa
 //	if data.Success == true {
 // 		fmt.Printf("%v\n", data.File)
 // 	}
-func (c *Client) File(id int) (FileResponse, int, *errs.Failure) {
+func (c *Client) File(id int) (FileResponse, int, error) {
 	var resp FileResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/files/%d", id))
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5181,7 +4637,7 @@ func (c *Client) File(id int) (FileResponse, int, *errs.Failure) {
 //  if status >= http.StatusBadRequest {
 // 	    fmt.Printf("%v", err.Error())
 //  }
-func (c *Client) FileDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
+func (c *Client) FileDelete(id int) (SuccessfulResponse, int, error) {
 	var resp SuccessfulResponse
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/files/%d/delete", id), strings.NewReader(""))
@@ -5192,11 +4648,6 @@ func (c *Client) FileDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5217,7 +4668,7 @@ func (c *Client) FileDelete(id int) (SuccessfulResponse, int, *errs.Failure) {
 //  if status >= http.StatusBadRequest {
 // 	    fmt.Printf("%v", err.Error())
 //  }
-func (c *Client) FileDownload(id int) (io.ReadCloser, int, *errs.Failure) {
+func (c *Client) FileDownload(id int) (io.ReadCloser, int, error) {
 	data, status, err := c.GetRequest(fmt.Sprintf("/files/%d/download", id))
 	if status != http.StatusOK {
 		return nil, status, err
@@ -5244,13 +4695,15 @@ func (c *Client) FileDownload(id int) (io.ReadCloser, int, *errs.Failure) {
 //  if status >= http.StatusBadRequest {
 // 	    fmt.Printf("%v", err.Error())
 //  }
-func (c *Client) FileEdit(id int, file File) (FileResponse, int, *errs.Failure) {
+func (c *Client) FileEdit(id int, file File) (FileResponse, int, error) {
 	var resp FileResponse
 
 	req, _ := json.Marshal(file)
-	data, status, err := c.PostRequest(fmt.Sprintf("/files/%d/edit", id), url.Values{
-		"file": {string(req)},
-	})
+	data, status, err := c.PostRequest(
+		fmt.Sprintf("/files/%d/edit", id), url.Values{
+			"file": {string(req)},
+		},
+	)
 
 	if err != nil && err.Error() != "" {
 		return resp, status, err
@@ -5258,11 +4711,6 @@ func (c *Client) FileEdit(id int, file File) (FileResponse, int, *errs.Failure)
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5290,24 +4738,19 @@ func (c *Client) FileEdit(id int, file File) (FileResponse, int, *errs.Failure)
 // 	for _, value := range data.CustomFields {
 //		fmt.Printf("%v\n", value)
 //	}
-func (c *Client) CustomFields(customFields CustomFieldsRequest) (CustomFieldsResponse, int, *errs.Failure) {
+func (c *Client) CustomFields(customFields CustomFieldsRequest) (CustomFieldsResponse, int, error) {
 	var resp CustomFieldsResponse
 
 	params, _ := query.Values(customFields)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/custom-fields?%s", params.Encode()))
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5336,24 +4779,21 @@ func (c *Client) CustomFields(customFields CustomFieldsRequest) (CustomFieldsRes
 //	for _, value := range data.CustomDictionaries {
 //		fmt.Printf("%v\n", value.Elements)
 //	}
-func (c *Client) CustomDictionaries(customDictionaries CustomDictionariesRequest) (CustomDictionariesResponse, int, *errs.Failure) {
+func (c *Client) CustomDictionaries(customDictionaries CustomDictionariesRequest) (
+	CustomDictionariesResponse, int, error,
+) {
 	var resp CustomDictionariesResponse
 
 	params, _ := query.Values(customDictionaries)
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/custom-fields/dictionaries?%s", params.Encode()))
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5391,7 +4831,7 @@ func (c *Client) CustomDictionaries(customDictionaries CustomDictionariesRequest
 //	If data.Success == true {
 //		fmt.Printf("%v", data.Code)
 //	}
-func (c *Client) CustomDictionariesCreate(customDictionary CustomDictionary) (CustomResponse, int, *errs.Failure) {
+func (c *Client) CustomDictionariesCreate(customDictionary CustomDictionary) (CustomResponse, int, error) {
 	var resp CustomResponse
 
 	costJSON, _ := json.Marshal(&customDictionary)
@@ -5402,17 +4842,12 @@ func (c *Client) CustomDictionariesCreate(customDictionary CustomDictionary) (Cu
 
 	data, status, err := c.PostRequest("/custom-fields/dictionaries/create", p)
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5437,22 +4872,17 @@ func (c *Client) CustomDictionariesCreate(customDictionary CustomDictionary) (Cu
 // 	If data.Success == true {
 // 		fmt.Printf("%v", data.CustomDictionary.Name)
 // 	}
-func (c *Client) CustomDictionary(code string) (CustomDictionaryResponse, int, *errs.Failure) {
+func (c *Client) CustomDictionary(code string) (CustomDictionaryResponse, int, error) {
 	var resp CustomDictionaryResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/custom-fields/dictionaries/%s", code))
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5490,7 +4920,7 @@ func (c *Client) CustomDictionary(code string) (CustomDictionaryResponse, int, *
 //	If data.Success == true {
 //		fmt.Printf("%v", data.Code)
 //	}
-func (c *Client) CustomDictionaryEdit(customDictionary CustomDictionary) (CustomResponse, int, *errs.Failure) {
+func (c *Client) CustomDictionaryEdit(customDictionary CustomDictionary) (CustomResponse, int, error) {
 	var resp CustomResponse
 
 	costJSON, _ := json.Marshal(&customDictionary)
@@ -5500,17 +4930,12 @@ func (c *Client) CustomDictionaryEdit(customDictionary CustomDictionary) (Custom
 	}
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/custom-fields/dictionaries/%s/edit", customDictionary.Code), p)
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5541,7 +4966,7 @@ func (c *Client) CustomDictionaryEdit(customDictionary CustomDictionary) (Custom
 // 	If data.Success == true {
 // 		fmt.Printf("%v", data.Code)
 // 	}
-func (c *Client) CustomFieldsCreate(customFields CustomFields) (CustomResponse, int, *errs.Failure) {
+func (c *Client) CustomFieldsCreate(customFields CustomFields) (CustomResponse, int, error) {
 	var resp CustomResponse
 
 	costJSON, _ := json.Marshal(&customFields)
@@ -5552,17 +4977,12 @@ func (c *Client) CustomFieldsCreate(customFields CustomFields) (CustomResponse,
 
 	data, status, err := c.PostRequest(fmt.Sprintf("/custom-fields/%s/create", customFields.Entity), p)
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5587,22 +5007,17 @@ func (c *Client) CustomFieldsCreate(customFields CustomFields) (CustomResponse,
 // 	If data.Success == true {
 // 		fmt.Printf("%v", data.CustomField)
 // 	}
-func (c *Client) CustomField(entity, code string) (CustomFieldResponse, int, *errs.Failure) {
+func (c *Client) CustomField(entity, code string) (CustomFieldResponse, int, error) {
 	var resp CustomFieldResponse
 
 	data, status, err := c.GetRequest(fmt.Sprintf("/custom-fields/%s/%s", entity, code))
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
 
@@ -5631,7 +5046,7 @@ func (c *Client) CustomField(entity, code string) (CustomFieldResponse, int, *er
 // 	If data.Success == true {
 // 		fmt.Printf("%v", data.Code)
 // 	}
-func (c *Client) CustomFieldEdit(customFields CustomFields) (CustomResponse, int, *errs.Failure) {
+func (c *Client) CustomFieldEdit(customFields CustomFields) (CustomResponse, int, error) {
 	var resp CustomResponse
 
 	costJSON, _ := json.Marshal(&customFields)
@@ -5640,18 +5055,15 @@ func (c *Client) CustomFieldEdit(customFields CustomFields) (CustomResponse, int
 		"customField": {string(costJSON[:])},
 	}
 
-	data, status, err := c.PostRequest(fmt.Sprintf("/custom-fields/%s/%s/edit", customFields.Entity, customFields.Code), p)
+	data, status, err := c.PostRequest(
+		fmt.Sprintf("/custom-fields/%s/%s/edit", customFields.Entity, customFields.Code), p,
+	)
 
-	if err.Error() != "" {
+	if err != nil {
 		return resp, status, err
 	}
 
 	json.Unmarshal(data, &resp)
 
-	if resp.Success == false {
-		buildErr(data, err)
-		return resp, status, err
-	}
-
 	return resp, status, nil
 }
diff --git a/v5/client_test.go b/v5/client_test.go
index 0e132a2..c8687d7 100644
--- a/v5/client_test.go
+++ b/v5/client_test.go
@@ -112,17 +112,13 @@ func TestClient_ApiVersionsVersions(t *testing.T) {
 		Reply(200).
 		BodyString(`{"success": true, "versions" : ["1.0", "4.0", "3.0", "4.0", "5.0"]}`)
 
-	data, status, err := c.APIVersions()
-	if err.Error() != "" {
+	data, _, err := c.APIVersions()
+	if err != nil {
 		t.Errorf("%v", err.Error())
 	}
 
-	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
-	}
-
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -133,20 +129,16 @@ func TestClient_ApiVersionsVersionsBadUrl(t *testing.T) {
 
 	gock.New(badURL).
 		Get("/api/api-versions").
-		Reply(200).
+		Reply(400).
 		BodyString(`{"success": false, "errorMsg" : "Account does not exist"}`)
 
-	data, status, err := c.APIVersions()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+	data, _, err := c.APIVersions()
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
-		t.Logf("%v", err.ApiError())
+		t.Logf("%v", err)
 	}
 }
 
@@ -160,17 +152,13 @@ func TestClient_ApiCredentialsCredentialsBadKey(t *testing.T) {
 
 	c := client()
 
-	data, status, err := c.APICredentials()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Logf("%v", err.ApiError())
+	data, _, err := c.APICredentials()
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
-		t.Logf("%v", err.ApiError())
+		t.Logf("%v", err)
 	}
 }
 
@@ -184,17 +172,13 @@ func TestClient_ApiCredentialsCredentials(t *testing.T) {
 
 	c := client()
 
-	data, status, err := c.APICredentials()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+	data, _, err := c.APICredentials()
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -217,16 +201,16 @@ func TestClient_CustomersCustomers(t *testing.T) {
 		Page: 3,
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Logf("%v", err.ApiError())
+		t.Logf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Logf("%v", err.ApiError())
+		t.Logf("%v", err)
 	}
 }
 
@@ -241,18 +225,14 @@ func TestClient_CustomersCustomers_Fail(t *testing.T) {
 
 	c := client()
 
-	data, status, err := c.Customers(CustomersRequest{
+	data, _, err := c.Customers(CustomersRequest{
 		Filter: CustomersFilter{
 			Ids: []string{codeFail},
 		},
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -296,16 +276,16 @@ func TestClient_CustomerChange(t *testing.T) {
 		BodyString(`{"success": true, "id": 123}`)
 
 	cr, sc, err := c.CustomerCreate(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if sc != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cr.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	f.ID = cr.ID
@@ -326,16 +306,16 @@ func TestClient_CustomerChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	ed, se, err := c.CustomerEdit(f, ByID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if se != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if ed.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -360,21 +340,17 @@ func TestClient_CustomerChange(t *testing.T) {
 			}
 		}`)
 
-	data, status, err := c.Customer(f.ExternalID, ByExternalID, "")
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+	data, _, err := c.Customer(f.ExternalID, ByExternalID, "")
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if !reflect.DeepEqual(data.Customer.Tags, f.Tags) {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -401,8 +377,8 @@ func TestClient_CustomerChange_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Parameter 'externalId' in 'customer' is missing"}`)
 
 	cr, sc, err := c.CustomerCreate(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if sc < http.StatusBadRequest {
@@ -431,8 +407,8 @@ func TestClient_CustomerChange_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
 	ed, se, err := c.CustomerEdit(f, ByID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if se < http.StatusBadRequest {
@@ -449,13 +425,9 @@ func TestClient_CustomerChange_Fail(t *testing.T) {
 		Reply(404).
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
-	data, status, err := c.Customer(codeFail, ByExternalID, "")
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.Customer(codeFail, ByExternalID, "")
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -492,16 +464,16 @@ func TestClient_CustomersUpload(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.CustomersUpload(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -524,13 +496,9 @@ func TestClient_CustomersUpload_Fail(t *testing.T) {
 		Reply(460).
 		BodyString(`{"success": false, "errorMsg": "Customers are loaded with errors"}`)
 
-	data, status, err := c.CustomersUpload(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CustomersUpload(customers)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -562,16 +530,16 @@ func TestClient_CustomersCombine(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.CustomersCombine(customers, resultCustomer)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -598,13 +566,9 @@ func TestClient_CustomersCombine_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Invalid input parameters"}`)
 
-	data, status, err := c.CustomersCombine([]Customer{{}, {}}, Customer{})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CustomersCombine([]Customer{{}, {}}, Customer{})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -636,16 +600,16 @@ func TestClient_CustomersFixExternalIds(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	fx, fe, err := c.CustomersFixExternalIds(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if fe != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if fx.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -669,13 +633,9 @@ func TestClient_CustomersFixExternalIds_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"id": "ID must be an integer"}}`)
 
-	data, status, err := c.CustomersFixExternalIds(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CustomersFixExternalIds(customers)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -699,16 +659,16 @@ func TestClient_CustomersHistory(t *testing.T) {
 		BodyString(`{"success": true, "history": [{"id": 1}]}`)
 
 	data, status, err := c.CustomersHistory(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.History) == 0 {
@@ -732,13 +692,9 @@ func TestClient_CustomersHistory_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"children[startDate]": "Значение недопустимо."}}`)
 
-	data, status, err := c.CustomersHistory(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CustomersHistory(f)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -765,16 +721,16 @@ func TestClient_CorporateCustomersList(t *testing.T) {
 		Page: 3,
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Logf("%v", err.ApiError())
+		t.Logf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Logf("%v", err.ApiError())
+		t.Logf("%v", err)
 	}
 }
 
@@ -861,16 +817,16 @@ func TestClient_CorporateCustomersCreate(t *testing.T) {
 
 	data, status, err := c.CorporateCustomerCreate(customer, "site")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -898,16 +854,16 @@ func TestClient_CorporateCustomersFixExternalIds(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	fx, fe, err := c.CorporateCustomersFixExternalIds(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if fe != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if fx.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -931,13 +887,9 @@ func TestClient_CorporateCustomersFixExternalIds_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"id": "ID must be an integer"}}`)
 
-	data, status, err := c.CorporateCustomersFixExternalIds(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CorporateCustomersFixExternalIds(customers)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -961,16 +913,16 @@ func TestClient_CorporateCustomersHistory(t *testing.T) {
 		BodyString(`{"success": true, "history": [{"id": 1}]}`)
 
 	data, status, err := c.CorporateCustomersHistory(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.History) == 0 {
@@ -994,13 +946,9 @@ func TestClient_CorporateCustomersHistory_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"children[startDate]": "Значение недопустимо."}}`)
 
-	data, status, err := c.CorporateCustomersHistory(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CorporateCustomersHistory(f)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -1049,16 +997,16 @@ func TestClient_CorporateCustomersNotes(t *testing.T) {
 		},
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Notes[0].Text != "<p>sample text</p>" {
@@ -1083,16 +1031,16 @@ func TestClient_CorporateCustomerNoteCreate(t *testing.T) {
 		},
 	}, "site")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.ID != 1 {
@@ -1112,16 +1060,16 @@ func TestClient_CorporateCustomerNoteDelete(t *testing.T) {
 
 	data, status, err := c.CorporateCustomerNoteDelete(1)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1152,16 +1100,16 @@ func TestClient_CorporateCustomersUpload(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.CorporateCustomersUpload(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1184,13 +1132,9 @@ func TestClient_CorporateCustomersUpload_Fail(t *testing.T) {
 		Reply(460).
 		BodyString(`{"success": false, "errorMsg": "Customers are loaded with errors"}`)
 
-	data, status, err := c.CorporateCustomersUpload(customers)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CorporateCustomersUpload(customers)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -1242,16 +1186,16 @@ func TestClient_CorporateCustomer(t *testing.T) {
 		`)
 
 	data, status, err := c.CorporateCustomer("ext-id", ByExternalID, "site")
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1301,16 +1245,16 @@ func TestClient_CorporateCustomerAddresses(t *testing.T) {
 		Page:  1,
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.Addresses) == 0 {
@@ -1333,16 +1277,16 @@ func TestClient_CorporateCustomerAddressesCreate(t *testing.T) {
 		Name: "New Address",
 	}, "site")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1367,16 +1311,16 @@ func TestClient_CorporateCustomerAddressesEdit(t *testing.T) {
 		"site",
 	)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1462,16 +1406,16 @@ func TestClient_CorporateCustomerCompanies(t *testing.T) {
 		Page:  1,
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.Companies) == 0 {
@@ -1493,16 +1437,16 @@ func TestClient_CorporateCustomerCompaniesCreate(t *testing.T) {
 		Name: "New Company",
 	}, "site")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1527,16 +1471,16 @@ func TestClient_CorporateCustomerCompaniesEdit(t *testing.T) {
 		"site",
 	)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1578,16 +1522,16 @@ func TestClient_CorporateCustomerContacts(t *testing.T) {
 		Page:   1,
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.Contacts) == 0 {
@@ -1616,16 +1560,16 @@ func TestClient_CorporateCustomerContactsCreate(t *testing.T) {
 		LastName:   "Person",
 	}, "site")
 
-	if createErr.Error() != "" {
-		t.Errorf("%v", createErr.Error())
+	if createErr != nil {
+		t.Errorf("%v", createErr)
 	}
 
 	if createStatus >= http.StatusBadRequest {
-		t.Errorf("%v", createErr.ApiError())
+		t.Errorf("%v", createErr)
 	}
 
 	if createResponse.Success != true {
-		t.Errorf("%v", createErr.ApiError())
+		t.Errorf("%v", createErr)
 	}
 
 	if createResponse.ID != 2 {
@@ -1641,16 +1585,16 @@ func TestClient_CorporateCustomerContactsCreate(t *testing.T) {
 		Companies: []IdentifiersPair{},
 	}, "site")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.ID != 3 {
@@ -1675,16 +1619,16 @@ func TestClient_CorporateCustomerContactsEdit(t *testing.T) {
 		},
 	}, "site")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("(%d) %v", status, err.ApiError())
+		t.Errorf("(%d) %v", status, err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.ID == 0 {
@@ -1708,16 +1652,16 @@ func TestClient_CorporateCustomerEdit(t *testing.T) {
 		Vip:        true,
 	}, ByExternalID, "site")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("(%d) %v", status, err.ApiError())
+		t.Errorf("(%d) %v", status, err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1733,20 +1677,20 @@ func TestClient_NotesNotes(t *testing.T) {
 		BodyString(`{"success": true, "notes": [{"id": 1}]}`)
 
 	data, status, err := c.CustomerNotes(NotesRequest{Page: 1})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.Notes) == 0 {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1761,15 +1705,11 @@ func TestClient_NotesNotes_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"children[createdAtFrom]": "This value is not valid."}}`)
 
-	data, status, err := c.CustomerNotes(NotesRequest{
+	data, _, err := c.CustomerNotes(NotesRequest{
 		Filter: NotesFilter{CreatedAtFrom: "2020-13-12"},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -1804,16 +1744,16 @@ func TestClient_NotesCreateDelete(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	noteCreateResponse, noteCreateStatus, err := c.CustomerNoteCreate(note)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if noteCreateStatus != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if noteCreateResponse.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	p = url.Values{
@@ -1828,17 +1768,17 @@ func TestClient_NotesCreateDelete(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	noteDeleteResponse, noteDeleteStatus, err := c.CustomerNoteDelete(noteCreateResponse.ID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if noteDeleteStatus != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if noteDeleteResponse.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1865,13 +1805,9 @@ func TestClient_NotesCreateDelete_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the entity format", "errors": {"customer": "Set one of the following fields: id, externalId"}}`)
 
-	data, status, err := c.CustomerNoteCreate(note)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CustomerNoteCreate(note)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -1890,8 +1826,8 @@ func TestClient_NotesCreateDelete_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Note not found map"}`)
 
 	noteDeleteResponse, noteDeleteStatus, err := c.CustomerNoteDelete(iCodeFail)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if noteDeleteStatus < http.StatusBadRequest {
@@ -1916,17 +1852,17 @@ func TestClient_OrdersOrders(t *testing.T) {
 		BodyString(`{"success": true, "orders":  [{"id": 1}]}`)
 
 	data, status, err := c.Orders(OrdersRequest{Filter: OrdersFilter{City: "Москва"}, Page: 1})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -1941,13 +1877,9 @@ func TestClient_OrdersOrders_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"children[attachments]": "SThis value is not valid."}}`)
 
-	data, status, err := c.Orders(OrdersRequest{Filter: OrdersFilter{Attachments: 7}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.Orders(OrdersRequest{Filter: OrdersFilter{Attachments: 7}})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2060,16 +1992,16 @@ func TestClient_OrderChange(t *testing.T) {
 }`)
 
 	cr, sc, err := c.OrderCreate(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if sc != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cr.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cr.Order.Number != "1A" {
@@ -2094,16 +2026,16 @@ func TestClient_OrderChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	ed, se, err := c.OrderEdit(f, ByID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if se != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if ed.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -2113,16 +2045,16 @@ func TestClient_OrderChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.Order(f.ExternalID, ByExternalID, "")
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2156,13 +2088,9 @@ func TestClient_OrderChange_Fail(t *testing.T) {
 		Reply(404).
 		BodyString(`{"success": false, "errorMsg": "Not found map"}`)
 
-	data, status, err := c.OrderEdit(f, ByID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.OrderEdit(f, ByID)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2199,17 +2127,17 @@ func TestClient_OrdersUpload(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.OrdersUpload(orders)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2240,13 +2168,9 @@ func TestClient_OrdersUpload_Fail(t *testing.T) {
 		Reply(460).
 		BodyString(`{"success": false, "errorMsg": "Orders are loaded with errors"}`)
 
-	data, status, err := c.OrdersUpload(orders)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.OrdersUpload(orders)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2275,17 +2199,17 @@ func TestClient_OrdersCombine(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.OrdersCombine("ours", Order{ID: 1}, Order{ID: 2})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2308,13 +2232,9 @@ func TestClient_OrdersCombine_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Invalid input parameters"}`)
 
-	data, status, err := c.OrdersCombine("ours", Order{}, Order{})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.OrdersCombine("ours", Order{}, Order{})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2345,17 +2265,17 @@ func TestClient_OrdersFixExternalIds(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	fx, fe, err := c.OrdersFixExternalIds(orders)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if fe != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if fx.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2377,13 +2297,9 @@ func TestClient_OrdersFixExternalIds_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Invalid input parameters"}`)
 
-	data, status, err := c.OrdersFixExternalIds(orders)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.OrdersFixExternalIds(orders)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2423,20 +2339,20 @@ func TestClient_OrdersStatuses(t *testing.T) {
 		IDs:         []int{1},
 		ExternalIDs: []string{"2"},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.Orders) == 0 {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2452,21 +2368,21 @@ func TestClient_OrdersHistory(t *testing.T) {
 		BodyString(`{"success": true, "history": [{"id": 1}]}`)
 
 	data, status, err := c.OrdersHistory(OrdersHistoryRequest{Filter: OrdersHistoryFilter{SinceID: 20}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.History) == 0 {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2481,13 +2397,9 @@ func TestClient_OrdersHistory_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"children[startDate]": "Значение недопустимо."}}`)
 
-	data, status, err := c.OrdersHistory(OrdersHistoryRequest{Filter: OrdersHistoryFilter{StartDate: "2020-13-12"}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.OrdersHistory(OrdersHistoryRequest{Filter: OrdersHistoryFilter{StartDate: "2020-13-12"}})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2521,16 +2433,16 @@ func TestClient_PaymentCreateEditDelete(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	paymentCreateResponse, status, err := c.OrderPaymentCreate(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if paymentCreateResponse.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	k := Payment{
@@ -2551,16 +2463,16 @@ func TestClient_PaymentCreateEditDelete(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	paymentEditResponse, status, err := c.OrderPaymentEdit(k, ByID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if paymentEditResponse.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	p = url.Values{
@@ -2575,16 +2487,16 @@ func TestClient_PaymentCreateEditDelete(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	paymentDeleteResponse, status, err := c.OrderPaymentDelete(paymentCreateResponse.ID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if paymentDeleteResponse.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2611,13 +2523,9 @@ func TestClient_PaymentCreateEditDelete_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the entity format", "errors": {"order": "Set one of the following fields: id, externalId, number"}}`)
 
-	data, status, err := c.OrderPaymentCreate(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.OrderPaymentCreate(f)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2642,8 +2550,8 @@ func TestClient_PaymentCreateEditDelete_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Payment not found"}`)
 
 	paymentEditResponse, status, err := c.OrderPaymentEdit(k, ByID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if status < http.StatusBadRequest {
@@ -2666,12 +2574,8 @@ func TestClient_PaymentCreateEditDelete_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Payment not found"}`)
 
 	paymentDeleteResponse, status, err := c.OrderPaymentDelete(iCodeFail)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if paymentDeleteResponse.Success != false {
@@ -2698,16 +2602,16 @@ func TestClient_TasksTasks(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.Tasks(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2727,13 +2631,9 @@ func TestClient_TasksTasks_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.Tasks(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.Tasks(f)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2763,16 +2663,16 @@ func TestClient_TaskChange(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	cr, sc, err := c.TaskCreate(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if sc != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cr.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	f.ID = cr.ID
@@ -2784,16 +2684,16 @@ func TestClient_TaskChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	gt, sg, err := c.Task(f.ID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if sg != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if gt.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	jr, _ = json.Marshal(f)
@@ -2809,17 +2709,17 @@ func TestClient_TaskChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.TaskEdit(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2845,13 +2745,9 @@ func TestClient_TaskChange_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Task is not loaded", "errors": {"performerId": "This value should not be blank."}}`)
 
-	data, status, err := c.TaskEdit(f)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.TaskEdit(f)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2872,17 +2768,17 @@ func TestClient_UsersUsers(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.Users(UsersRequest{Filter: UsersFilter{Active: 1}, Page: 1})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2898,13 +2794,9 @@ func TestClient_UsersUsers_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters", "errors": {"active": "he value you selected is not a valid choice."}}`)
 
-	data, status, err := c.Users(UsersRequest{Filter: UsersFilter{Active: 3}, Page: 1})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.Users(UsersRequest{Filter: UsersFilter{Active: 3}, Page: 1})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2923,17 +2815,17 @@ func TestClient_UsersUser(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.User(user)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -2947,13 +2839,9 @@ func TestClient_UsersUser_Fail(t *testing.T) {
 		Reply(404).
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
-	data, status, err := c.User(iCodeFail)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.User(iCodeFail)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -2973,16 +2861,16 @@ func TestClient_UsersGroups(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.UserGroups(UserGroupsRequest{Page: 1})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3003,17 +2891,16 @@ func TestClient_UsersUpdate(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.UserStatus(user, "busy")
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3033,13 +2920,9 @@ func TestClient_UsersUpdate_Fail(t *testing.T) {
 		Reply(404).
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
-	data, status, err := c.UserStatus(iCodeFail, "busy")
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.UserStatus(iCodeFail, "busy")
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -3058,16 +2941,16 @@ func TestClient_StaticticsUpdate(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.StaticticsUpdate()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3082,16 +2965,16 @@ func TestClient_Countries(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.Couriers()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3106,16 +2989,16 @@ func TestClient_CostGroups(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.CostGroups()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3130,16 +3013,16 @@ func TestClient_CostItems(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.CostItems()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3154,16 +3037,16 @@ func TestClient_Couriers(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.Couriers()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3178,16 +3061,16 @@ func TestClient_DeliveryService(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.DeliveryServices()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3202,16 +3085,16 @@ func TestClient_DeliveryTypes(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.DeliveryTypes()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3226,16 +3109,16 @@ func TestClient_LegalEntities(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.LegalEntities()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3250,16 +3133,16 @@ func TestClient_OrderMethods(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.OrderMethods()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3285,16 +3168,16 @@ func TestClient_OrderPaymentEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.OrderPaymentEdit(payment, "externalId")
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3309,16 +3192,16 @@ func TestClient_OrderTypes(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.OrderTypes()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3333,16 +3216,16 @@ func TestClient_PaymentStatuses(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.PaymentStatuses()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3357,16 +3240,16 @@ func TestClient_PaymentTypes(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.PaymentTypes()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3381,16 +3264,16 @@ func TestClient_PriceTypes(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.PriceTypes()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3405,16 +3288,16 @@ func TestClient_ProductStatuses(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.ProductStatuses()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3429,16 +3312,16 @@ func TestClient_Statuses(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.Statuses()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3453,16 +3336,16 @@ func TestClient_StatusGroups(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.StatusGroups()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3477,16 +3360,16 @@ func TestClient_Sites(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.Sites()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3501,16 +3384,16 @@ func TestClient_Stores(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.Stores()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3542,16 +3425,16 @@ func TestClient_CostGroupItemEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.CostGroupEdit(costGroup)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	costItem := CostItem{
@@ -3577,17 +3460,17 @@ func TestClient_CostGroupItemEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	idata, st, err := c.CostItemEdit(costItem)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if idata.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3616,13 +3499,9 @@ func TestClient_CostGroupItemEdit_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.CostGroupEdit(costGroup)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CostGroupEdit(costGroup)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -3652,8 +3531,8 @@ func TestClient_CostGroupItemEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
 	idata, st, err := c.CostItemEdit(costItem)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -3691,16 +3570,16 @@ func TestClient_Courier(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	data, st, err := c.CourierCreate(cur)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	cur.ID = data.ID
@@ -3720,17 +3599,17 @@ func TestClient_Courier(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	idata, st, err := c.CourierEdit(cur)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if idata.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3753,8 +3632,8 @@ func TestClient_Courier_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Errors in the entity format", "errors": {"firstName": "Specify the first name"}}`)
 
 	data, st, err := c.CourierCreate(Courier{})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -3780,8 +3659,8 @@ func TestClient_Courier_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "An attempt was made to edit a nonexistent record"}`)
 
 	idata, st, err := c.CourierEdit(cur)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -3818,17 +3697,17 @@ func TestClient_DeliveryServiceEdit(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	data, st, err := c.DeliveryServiceEdit(deliveryService)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3855,8 +3734,8 @@ func TestClient_DeliveryServiceEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.DeliveryServiceEdit(deliveryService)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -3898,17 +3777,17 @@ func TestClient_DeliveryTypeEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.DeliveryTypeEdit(deliveryType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -3939,8 +3818,8 @@ func TestClient_DeliveryTypeEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.DeliveryTypeEdit(deliveryType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -3977,17 +3856,17 @@ func TestClient_OrderMethodEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.OrderMethodEdit(orderMethod)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4015,8 +3894,8 @@ func TestClient_OrderMethodEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.OrderMethodEdit(orderMethod)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4054,17 +3933,17 @@ func TestClient_OrderTypeEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.OrderTypeEdit(orderType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4091,8 +3970,8 @@ func TestClient_OrderTypeEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.OrderTypeEdit(orderType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4132,17 +4011,17 @@ func TestClient_PaymentStatusEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.PaymentStatusEdit(paymentStatus)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4172,8 +4051,8 @@ func TestClient_PaymentStatusEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.PaymentStatusEdit(paymentStatus)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4210,17 +4089,17 @@ func TestClient_PaymentTypeEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.PaymentTypeEdit(paymentType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4248,8 +4127,8 @@ func TestClient_PaymentTypeEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.PaymentTypeEdit(paymentType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4285,16 +4164,16 @@ func TestClient_PriceTypeEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.PriceTypeEdit(priceType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4321,8 +4200,8 @@ func TestClient_PriceTypeEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.PriceTypeEdit(priceType)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4359,16 +4238,16 @@ func TestClient_ProductStatusEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.ProductStatusEdit(productStatus)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4396,8 +4275,8 @@ func TestClient_ProductStatusEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.ProductStatusEdit(productStatus)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4434,17 +4313,17 @@ func TestClient_StatusEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.StatusEdit(status)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4473,8 +4352,8 @@ func TestClient_StatusEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.StatusEdit(status)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4511,12 +4390,12 @@ func TestClient_SiteEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, _, err := c.SiteEdit(site)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if data.Success == false {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4545,8 +4424,8 @@ func TestClient_SiteEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Method Not Allowed"}`)
 
 	data, _, err := c.SiteEdit(site)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -4581,16 +4460,16 @@ func TestClient_StoreEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.StoreEdit(store)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4620,8 +4499,8 @@ func TestClient_StoreEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	data, st, err := c.StoreEdit(store)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4644,16 +4523,16 @@ func TestClient_Units(t *testing.T) {
 		BodyString(`{"success": true, "units": []}`)
 
 	data, st, err := c.Units()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if st != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4684,16 +4563,16 @@ func TestClient_UnitsEdit(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, st, err := c.UnitEdit(unit)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[st] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4721,8 +4600,8 @@ func TestClient_UnitEdit_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Method not found"}`)
 
 	data, st, err := c.UnitEdit(unit)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if st < http.StatusBadRequest {
@@ -4758,16 +4637,16 @@ func TestClient_PackChange(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	p, status, err := c.PackCreate(pack)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if p.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -4776,16 +4655,16 @@ func TestClient_PackChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	s, status, err := c.Pack(p.ID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if s.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	jr, _ = json.Marshal(&Pack{ID: p.ID, Quantity: 2})
@@ -4802,16 +4681,16 @@ func TestClient_PackChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	e, status, err := c.PackEdit(Pack{ID: p.ID, Quantity: 2})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if e.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -4821,16 +4700,16 @@ func TestClient_PackChange(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	d, status, err := c.PackDelete(p.ID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if d.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4859,8 +4738,8 @@ func TestClient_PackChange_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Errors in the entity format"}`)
 
 	p, status, err := c.PackCreate(pack)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status < http.StatusBadRequest {
@@ -4877,12 +4756,8 @@ func TestClient_PackChange_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Errors in the entity format"}`)
 
 	s, status, err := c.Pack(iCodeFail)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if s.Success != false {
@@ -4903,12 +4778,8 @@ func TestClient_PackChange_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Pack with id 123123 not found"}`)
 
 	e, status, err := c.PackEdit(Pack{ID: iCodeFail, Quantity: 2})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if e.Success != false {
@@ -4922,12 +4793,8 @@ func TestClient_PackChange_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Pack not found"}`)
 
 	d, status, err := c.PackDelete(iCodeFail)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if d.Success != false {
@@ -4947,21 +4814,21 @@ func TestClient_PacksHistory(t *testing.T) {
 		BodyString(`{"success": true, "history": [{"id": 1}]}`)
 
 	data, status, err := c.PacksHistory(PacksHistoryRequest{Filter: OrdersHistoryFilter{SinceID: 5}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if len(data.History) == 0 {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -4976,13 +4843,9 @@ func TestClient_PacksHistory_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.PacksHistory(PacksHistoryRequest{Filter: OrdersHistoryFilter{StartDate: "2020-13-12"}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.PacksHistory(PacksHistoryRequest{Filter: OrdersHistoryFilter{StartDate: "2020-13-12"}})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -5002,17 +4865,17 @@ func TestClient_Packs(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	data, status, err := c.Packs(PacksRequest{Filter: PacksFilter{}, Page: 1})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5027,13 +4890,9 @@ func TestClient_Packs_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.Packs(PacksRequest{Filter: PacksFilter{ShipmentDateFrom: "2020-13-12"}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.Packs(PacksRequest{Filter: PacksFilter{ShipmentDateFrom: "2020-13-12"}})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -5054,17 +4913,17 @@ func TestClient_Inventories(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	data, status, err := c.Inventories(InventoriesRequest{Filter: InventoriesFilter{Details: 1}, Page: 1})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5079,13 +4938,9 @@ func TestClient_Inventories_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.Inventories(InventoriesRequest{Filter: InventoriesFilter{Sites: []string{codeFail}}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.Inventories(InventoriesRequest{Filter: InventoriesFilter{Sites: []string{codeFail}}})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -5104,17 +4959,17 @@ func TestClient_Segments(t *testing.T) {
 		BodyString(`{"success": true, "id": 1}`)
 
 	data, status, err := c.Segments(SegmentsRequest{})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5146,16 +5001,16 @@ func TestClient_Settings(t *testing.T) {
 `)
 
 	data, status, err := c.Settings()
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status >= http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Settings.DefaultCurrency.Value != "RUB" {
@@ -5182,13 +5037,9 @@ func TestClient_Segments_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.Segments(SegmentsRequest{Filter: SegmentsFilter{Active: 3}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.Segments(SegmentsRequest{Filter: SegmentsFilter{Active: 3}})
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if data.Success != false {
@@ -5229,16 +5080,16 @@ func TestClient_IntegrationModule(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	m, status, err := c.IntegrationModuleEdit(integrationModule)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusCreated {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if m.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -5247,16 +5098,16 @@ func TestClient_IntegrationModule(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	g, status, err := c.IntegrationModule(code)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if g.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5292,8 +5143,8 @@ func TestClient_IntegrationModule_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	m, status, err := c.IntegrationModuleEdit(integrationModule)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if status < http.StatusBadRequest {
@@ -5310,12 +5161,8 @@ func TestClient_IntegrationModule_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
 	g, status, err := c.IntegrationModule(code)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if g.Success != false {
@@ -5339,17 +5186,17 @@ func TestClient_ProductsGroup(t *testing.T) {
 			Active: 1,
 		},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if g.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5369,8 +5216,8 @@ func TestClient_ProductsGroup_Fail(t *testing.T) {
 			Active: 3,
 		},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if status < http.StatusBadRequest {
@@ -5400,17 +5247,17 @@ func TestClient_Products(t *testing.T) {
 			MinPrice: 1,
 		},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if g.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5428,8 +5275,8 @@ func TestClient_Products_Fail(t *testing.T) {
 	g, status, err := c.Products(ProductsRequest{
 		Filter: ProductsFilter{Active: 3},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if status < http.StatusBadRequest {
@@ -5460,16 +5307,16 @@ func TestClient_ProductsProperties(t *testing.T) {
 			Sites: sites,
 		},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if g.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5497,16 +5344,16 @@ func TestClient_DeliveryTracking(t *testing.T) {
 		}},
 	}}, "subcode")
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if g.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5526,16 +5373,16 @@ func TestClient_DeliveryShipments(t *testing.T) {
 			DateFrom: "2017-10-10",
 		},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if g.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5555,8 +5402,8 @@ func TestClient_DeliveryShipments_Fail(t *testing.T) {
 			Stores: []string{codeFail},
 		},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
 	if status < http.StatusBadRequest {
@@ -5595,16 +5442,16 @@ func TestClient_Cost(t *testing.T) {
 
 	data, status, err := c.CostCreate(costRecord)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	id := data.ID
@@ -5625,16 +5472,16 @@ func TestClient_Cost(t *testing.T) {
 		Page:  1,
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if costs.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -5644,16 +5491,16 @@ func TestClient_Cost(t *testing.T) {
 
 	cost, status, err := c.Cost(id)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cost.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	costRecord.DateFrom = "2018-04-09"
@@ -5675,16 +5522,16 @@ func TestClient_Cost(t *testing.T) {
 
 	costEdit, status, err := c.CostEdit(id, costRecord)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if costEdit.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	j, _ := json.Marshal(&id)
@@ -5702,16 +5549,16 @@ func TestClient_Cost(t *testing.T) {
 
 	costDelete, status, err := c.CostDelete(id)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if costDelete.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5740,17 +5587,13 @@ func TestClient_Cost_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Cost is not loaded"}`)
 
-	data, status, err := c.CostCreate(costRecord)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	data, _, err := c.CostCreate(costRecord)
+	if err == nil {
+		t.Error("Error must be return")
 	}
 
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
-	}
-
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	id := data.ID
@@ -5764,8 +5607,8 @@ func TestClient_Cost_Fail(t *testing.T) {
 	costs, status, err := c.Costs(CostsRequest{
 		Filter: CostsFilter{Sites: []string{codeFail}},
 	})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status < http.StatusBadRequest {
@@ -5782,12 +5625,8 @@ func TestClient_Cost_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
 	cost, status, err := c.Cost(id)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if cost.Success != false {
@@ -5813,12 +5652,8 @@ func TestClient_Cost_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Cost is not loaded"}`)
 
 	costEdit, status, err := c.CostEdit(id, costRecord)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if costEdit.Success != false {
@@ -5838,12 +5673,8 @@ func TestClient_Cost_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
 	costDelete, status, err := c.CostDelete(id)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if costDelete.Success != false {
@@ -5891,17 +5722,17 @@ func TestClient_CostsUpload(t *testing.T) {
 
 	data, status, err := c.CostsUpload(costsUpload)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	ids := data.UploadedCosts
@@ -5920,17 +5751,17 @@ func TestClient_CostsUpload(t *testing.T) {
 		BodyString(`{"success": true}`)
 
 	costsDelete, status, err := c.CostsDelete(ids)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if costsDelete.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -5964,13 +5795,9 @@ func TestClient_CostsUpload_Fail(t *testing.T) {
 		Reply(460).
 		BodyString(`{"success": false, "errorMsg": "Costs are loaded with errors"}`)
 
-	data, status, err := c.CostsUpload(costsUpload)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CostsUpload(costsUpload)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != false {
@@ -5993,8 +5820,8 @@ func TestClient_CostsUpload_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Expected array, but got NULL: null"}`)
 
 	costsDelete, status, err := c.CostsDelete(ids)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status < http.StatusBadRequest {
@@ -6029,7 +5856,7 @@ func TestClient_Files(t *testing.T) {
 	})
 
 	if status != 200 {
-		t.Errorf("%v %v", err.Error(), err.ApiError())
+		t.Errorf("%v %v", err.Error(), err)
 	}
 }
 
@@ -6045,16 +5872,16 @@ func TestClient_FileUpload(t *testing.T) {
 		BodyString(`{"success": true, "file": {"id": 1}}`)
 
 	data, status, err := c.FileUpload(file)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.File.ID != 1 {
@@ -6074,8 +5901,8 @@ func TestClient_FileUploadFail(t *testing.T) {
 		BodyString(`{"success":false,"errorMsg":"Your account doesn't have enough money to upload files."}`)
 
 	_, status, err := c.FileUpload(file)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusBadRequest {
@@ -6115,16 +5942,16 @@ func TestClient_File(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not Found"}`)
 
 	s, status, err := c.File(fileResponse.File.ID)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if s.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if s.File.ID != fileResponse.File.ID {
@@ -6132,8 +5959,8 @@ func TestClient_File(t *testing.T) {
 	}
 
 	s, status, err = c.File(invalidFile)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusNotFound {
@@ -6165,34 +5992,26 @@ func TestClient_FileDelete(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not Found"}`)
 
 	data, status, err := c.FileDelete(successful)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
-	data, status, err = c.FileDelete(badRequest)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	data, _, err = c.FileDelete(badRequest)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
-	if status != http.StatusBadRequest {
-		t.Errorf("status should be `%d`, got `%d` instead", http.StatusBadRequest, status)
-	}
-
-	data, status, err = c.FileDelete(notFound)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status != http.StatusNotFound {
-		t.Errorf("status should be `%d`, got `%d` instead", http.StatusNotFound, status)
+	data, _, err = c.FileDelete(notFound)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 }
 
@@ -6215,17 +6034,17 @@ func TestClient_FileDownload(t *testing.T) {
 		BodyString("")
 
 	data, status, err := c.FileDownload(successful)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
-	fetchedByte, errr := ioutil.ReadAll(data)
-	if errr != nil {
-		t.Error(errr)
+	fetchedByte, err := ioutil.ReadAll(data)
+	if err != nil {
+		t.Error(err)
 	}
 
 	fetched := string(fetchedByte)
@@ -6234,8 +6053,8 @@ func TestClient_FileDownload(t *testing.T) {
 	}
 
 	data, status, err = c.FileDownload(fail)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusBadRequest {
@@ -6266,25 +6085,25 @@ func TestClient_FileEdit(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not Found"}`)
 
 	data, status, err := c.FileEdit(successful, *resp.File)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if status != http.StatusOK {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.File.Filename != resp.File.Filename {
 		t.Errorf("filename should be `%s`, got `%s` instead", resp.File.Filename, data.File.Filename)
 	}
 
-	data, status, err = c.FileEdit(fail, *resp.File)
-	if status != http.StatusNotFound {
-		t.Errorf("status should be `%d`, got `%d` instead", http.StatusNotFound, status)
+	data, _, err = c.FileEdit(fail, *resp.File)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 }
 
@@ -6300,16 +6119,16 @@ func TestClient_CustomFields(t *testing.T) {
 
 	data, status, err := c.CustomFields(CustomFieldsRequest{})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -6324,13 +6143,9 @@ func TestClient_CustomFields_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.CustomFields(CustomFieldsRequest{Filter: CustomFieldsFilter{Type: codeFail}})
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CustomFields(CustomFieldsRequest{Filter: CustomFieldsFilter{Type: codeFail}})
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != false {
@@ -6371,16 +6186,16 @@ func TestClient_CustomDictionariesCreate(t *testing.T) {
 
 	data, status, err := c.CustomDictionariesCreate(customDictionary)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -6399,17 +6214,17 @@ func TestClient_CustomDictionariesCreate(t *testing.T) {
 		Page:  1,
 	})
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cds.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -6419,12 +6234,12 @@ func TestClient_CustomDictionariesCreate(t *testing.T) {
 
 	cd, status, err := c.CustomDictionary(code)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if cd.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	customDictionary.Name = "test223"
@@ -6450,16 +6265,16 @@ func TestClient_CustomDictionariesCreate(t *testing.T) {
 
 	cde, status, err := c.CustomDictionaryEdit(customDictionary)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cde.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -6492,9 +6307,9 @@ func TestClient_CustomDictionariesCreate_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.CustomDictionariesCreate(customDictionary)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	data, _, err := c.CustomDictionariesCreate(customDictionary)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != false {
@@ -6507,8 +6322,8 @@ func TestClient_CustomDictionariesCreate_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
 	cd, status, err := c.CustomDictionary(codeFail)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if cd.Success != false {
@@ -6536,12 +6351,12 @@ func TestClient_CustomDictionariesCreate_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	cde, status, err := c.CustomDictionaryEdit(customDictionary)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status < http.StatusBadRequest {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if cde.Success != false {
@@ -6578,17 +6393,17 @@ func TestClient_CustomFieldsCreate(t *testing.T) {
 
 	data, status, err := c.CustomFieldsCreate(customFields)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != true {
 
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	gock.New(crmURL).
@@ -6598,16 +6413,16 @@ func TestClient_CustomFieldsCreate(t *testing.T) {
 
 	customField, status, err := c.CustomField("order", codeCustomField)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if customField.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	customFields.DisplayArea = "delivery"
@@ -6627,16 +6442,16 @@ func TestClient_CustomFieldsCreate(t *testing.T) {
 
 	customFieldEdit, status, err := c.CustomFieldEdit(customFields)
 
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err != nil {
+		t.Errorf("%v", err)
 	}
 
 	if !statuses[status] {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 
 	if customFieldEdit.Success != true {
-		t.Errorf("%v", err.ApiError())
+		t.Errorf("%v", err)
 	}
 }
 
@@ -6667,13 +6482,9 @@ func TestClient_CustomFieldsCreate_Fail(t *testing.T) {
 		Reply(400).
 		BodyString(`{"success": false, "errorMsg": "Errors in the input parameters"}`)
 
-	data, status, err := c.CustomFieldsCreate(customFields)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	data, _, err := c.CustomFieldsCreate(customFields)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if data.Success != false {
@@ -6686,8 +6497,8 @@ func TestClient_CustomFieldsCreate_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "Not found"}`)
 
 	customField, status, err := c.CustomField("order", codeCustomField)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if status < http.StatusBadRequest {
@@ -6714,12 +6525,8 @@ func TestClient_CustomFieldsCreate_Fail(t *testing.T) {
 		BodyString(`{"success": false, "errorMsg": "API method not found"}`)
 
 	customFieldEdit, status, err := c.CustomFieldEdit(customFields)
-	if err.Error() != "" {
-		t.Errorf("%v", err.Error())
-	}
-
-	if status < http.StatusBadRequest {
-		t.Error(statusFail)
+	if err == nil {
+		t.Errorf("%v", err)
 	}
 
 	if customFieldEdit.Success != false {
diff --git a/v5/error.go b/v5/error.go
new file mode 100644
index 0000000..cbdc9df
--- /dev/null
+++ b/v5/error.go
@@ -0,0 +1,32 @@
+package v5
+
+import "encoding/json"
+
+// APIErrorsList struct.
+type APIErrorsList map[string]string
+
+// APIError struct.
+type APIError struct {
+	SuccessfulResponse
+	ErrorMsg string        `json:"errorMsg,omitempty"`
+	Errors   APIErrorsList `json:"errors,omitempty"`
+}
+
+func (e *APIError) Error() string {
+	return e.ErrorMsg
+}
+
+func NewAPIError(dataResponse []byte) error {
+	a := &APIError{}
+
+	if len(dataResponse) > 0 && dataResponse[0] == '<' {
+		a.ErrorMsg = "Account does not exist."
+		return a
+	}
+
+	if err := json.Unmarshal(dataResponse, a); err != nil {
+		return err
+	}
+
+	return a
+}
diff --git a/v5/error_test.go b/v5/error_test.go
new file mode 100644
index 0000000..989b8e3
--- /dev/null
+++ b/v5/error_test.go
@@ -0,0 +1,54 @@
+package v5
+
+import (
+	"reflect"
+	"testing"
+
+	"golang.org/x/xerrors"
+)
+
+func TestFailure_ApiErrorsSlice(t *testing.T) {
+	b := []byte(`{"success": false,
+				"errorMsg": "Failed to activate module",
+				"errors": [
+					"Your account has insufficient funds to activate integration module",
+					"Test error"
+				]}`)
+	expected := APIErrorsList{
+		"0": "Your account has insufficient funds to activate integration module",
+		"1": "Test error",
+	}
+
+	var expEr *APIError
+	e := NewAPIError(b)
+
+	if xerrors.As(e, &expEr) {
+		if eq := reflect.DeepEqual(expEr.Errors, expected); eq != true {
+			t.Errorf("%+v", eq)
+		}
+	} else {
+		t.Errorf("Error must be type of APIError: %v", e)
+	}
+}
+
+func TestFailure_ApiErrorsMap(t *testing.T) {
+	b := []byte(`{"success": false,
+				"errorMsg": "Failed to activate module",
+				"errors": {"id": "ID must be an integer", "test": "Test error"}}`,
+	)
+	expected := APIErrorsList{
+		"id":   "ID must be an integer",
+		"test": "Test error",
+	}
+
+	var expEr *APIError
+	e := NewAPIError(b)
+
+	if xerrors.As(e, &expEr) {
+		if eq := reflect.DeepEqual(expEr.Errors, expected); eq != true {
+			t.Errorf("%+v", eq)
+		}
+	} else {
+		t.Errorf("Error must be type of APIError: %v", e)
+	}
+}
diff --git a/v5/filters.go b/v5/filters.go
index 6a653bd..1956ac8 100644
--- a/v5/filters.go
+++ b/v5/filters.go
@@ -1,6 +1,6 @@
 package v5
 
-// CustomersFilter type
+// CustomersFilter type.
 type CustomersFilter struct {
 	Ids                        []string          `url:"ids,omitempty,brackets"`
 	ExternalIds                []string          `url:"externalIds,omitempty,brackets"`
@@ -57,7 +57,7 @@ type CustomersFilter struct {
 	CustomFields               map[string]string `url:"customFields,omitempty,brackets"`
 }
 
-// CorporateCustomersFilter type
+// CorporateCustomersFilter type.
 type CorporateCustomersFilter struct {
 	ContragentName        string            `url:"contragentName,omitempty"`
 	ContragentInn         string            `url:"contragentInn,omitempty"`
@@ -99,7 +99,7 @@ type CorporateCustomersFilter struct {
 	CustomFields          map[string]string `url:"customFields,omitempty,brackets"`
 }
 
-// CorporateCustomersNotesFilter type
+// CorporateCustomersNotesFilter type.
 type CorporateCustomersNotesFilter struct {
 	Ids                 []string `url:"ids,omitempty,brackets"`
 	CustomerIds         []string `url:"ids,omitempty,brackets"`
@@ -110,7 +110,7 @@ type CorporateCustomersNotesFilter struct {
 	CreatedAtTo         string   `url:"createdAtTo,omitempty"`
 }
 
-// CorporateCustomerAddressesFilter type
+// CorporateCustomerAddressesFilter type.
 type CorporateCustomerAddressesFilter struct {
 	Ids    []string `url:"ids,omitempty,brackets"`
 	Name   string   `url:"name,omitempty"`
@@ -118,13 +118,13 @@ type CorporateCustomerAddressesFilter struct {
 	Region string   `url:"region,omitempty"`
 }
 
-// IdentifiersPairFilter type
+// IdentifiersPairFilter type.
 type IdentifiersPairFilter struct {
 	Ids         []string `url:"ids,omitempty,brackets"`
 	ExternalIds []string `url:"externalIds,omitempty,brackets"`
 }
 
-// CustomersHistoryFilter type
+// CustomersHistoryFilter type.
 type CustomersHistoryFilter struct {
 	CustomerID         int    `url:"customerId,omitempty"`
 	SinceID            int    `url:"sinceId,omitempty"`
@@ -133,7 +133,7 @@ type CustomersHistoryFilter struct {
 	EndDate            string `url:"endDate,omitempty"`
 }
 
-// CorporateCustomersHistoryFilter type
+// CorporateCustomersHistoryFilter type.
 type CorporateCustomersHistoryFilter struct {
 	CustomerID         int      `url:"customerId,omitempty"`
 	SinceID            int      `url:"sinceId,omitempty"`
@@ -143,7 +143,7 @@ type CorporateCustomersHistoryFilter struct {
 	EndDate            string   `url:"endDate,omitempty"`
 }
 
-// OrdersFilter type
+// OrdersFilter type.
 type OrdersFilter struct {
 	Ids                            []int             `url:"ids,omitempty,brackets"`
 	ExternalIds                    []string          `url:"externalIds,omitempty,brackets"`
@@ -234,7 +234,7 @@ type OrdersFilter struct {
 	CustomFields                   map[string]string `url:"customFields,omitempty,brackets"`
 }
 
-// OrdersHistoryFilter type
+// OrdersHistoryFilter type.
 type OrdersHistoryFilter struct {
 	OrderID         int    `url:"orderId,omitempty"`
 	SinceID         int    `url:"sinceId,omitempty"`
@@ -243,7 +243,7 @@ type OrdersHistoryFilter struct {
 	EndDate         string `url:"endDate,omitempty"`
 }
 
-// UsersFilter type
+// UsersFilter type.
 type UsersFilter struct {
 	Email         string   `url:"email,omitempty"`
 	Status        string   `url:"status,omitempty"`
@@ -256,7 +256,7 @@ type UsersFilter struct {
 	Groups        []string `url:"groups,omitempty,brackets"`
 }
 
-// TasksFilter type
+// TasksFilter type.
 type TasksFilter struct {
 	OrderNumber string `url:"orderNumber,omitempty"`
 	Status      string `url:"status,omitempty"`
@@ -268,7 +268,7 @@ type TasksFilter struct {
 	Performers  []int  `url:"performers,omitempty,brackets"`
 }
 
-// NotesFilter type
+// NotesFilter type.
 type NotesFilter struct {
 	Ids                 []int    `url:"ids,omitempty,brackets"`
 	CustomerIds         []int    `url:"customerIds,omitempty,brackets"`
@@ -279,7 +279,7 @@ type NotesFilter struct {
 	CreatedAtTo         string   `url:"createdAtTo,omitempty"`
 }
 
-// SegmentsFilter type
+// SegmentsFilter type.
 type SegmentsFilter struct {
 	Ids               []int  `url:"ids,omitempty,brackets"`
 	Active            int    `url:"active,omitempty"`
@@ -291,7 +291,7 @@ type SegmentsFilter struct {
 	DateTo            string `url:"dateTo,omitempty"`
 }
 
-// PacksFilter type
+// PacksFilter type.
 type PacksFilter struct {
 	Ids                []int    `url:"ids,omitempty,brackets"`
 	Stores             []string `url:"stores,omitempty"`
@@ -306,7 +306,7 @@ type PacksFilter struct {
 	DeliveryNoteNumber string   `url:"deliveryNoteNumber,omitempty"`
 }
 
-// InventoriesFilter type
+// InventoriesFilter type.
 type InventoriesFilter struct {
 	Ids               []int    `url:"ids,omitempty,brackets"`
 	ProductExternalID string   `url:"productExternalId,omitempty"`
@@ -319,7 +319,7 @@ type InventoriesFilter struct {
 	Sites             []string `url:"sites,omitempty,brackets"`
 }
 
-// ProductsGroupsFilter type
+// ProductsGroupsFilter type.
 type ProductsGroupsFilter struct {
 	Ids           []int    `url:"ids,omitempty,brackets"`
 	Sites         []string `url:"sites,omitempty,brackets"`
@@ -327,7 +327,7 @@ type ProductsGroupsFilter struct {
 	ParentGroupID string   `url:"parentGroupId,omitempty"`
 }
 
-// ProductsFilter type
+// ProductsFilter type.
 type ProductsFilter struct {
 	Ids              []int             `url:"ids,omitempty,brackets"`
 	OfferIds         []int             `url:"offerIds,omitempty,brackets"`
@@ -355,14 +355,14 @@ type ProductsFilter struct {
 	Properties       map[string]string `url:"properties,omitempty,brackets"`
 }
 
-// ProductsPropertiesFilter type
+// ProductsPropertiesFilter type.
 type ProductsPropertiesFilter struct {
 	Code  string   `url:"code,omitempty"`
 	Name  string   `url:"name,omitempty"`
 	Sites []string `url:"sites,omitempty,brackets"`
 }
 
-// ShipmentFilter type
+// ShipmentFilter type.
 type ShipmentFilter struct {
 	Ids           []int    `url:"ids,omitempty,brackets"`
 	ExternalID    string   `url:"externalId,omitempty"`
@@ -375,7 +375,7 @@ type ShipmentFilter struct {
 	Statuses      []string `url:"statuses,omitempty,brackets"`
 }
 
-// CostsFilter type
+// CostsFilter type.
 type CostsFilter struct {
 	MinSumm          string   `url:"minSumm,omitempty"`
 	MaxSumm          string   `url:"maxSumm,omitempty"`
@@ -395,7 +395,7 @@ type CostsFilter struct {
 	OrderExternalIds []string `url:"orderIds,omitempty,brackets"`
 }
 
-// FilesFilter type
+// FilesFilter type.
 type FilesFilter struct {
 	Ids                 []int    `url:"ids,omitempty,brackets"`
 	OrderIds            []int    `url:"orderIds,omitempty,brackets"`
@@ -412,7 +412,7 @@ type FilesFilter struct {
 	Sites               []string `url:"sites,omitempty,brackets"`
 }
 
-// CustomFieldsFilter type
+// CustomFieldsFilter type.
 type CustomFieldsFilter struct {
 	Name        string `url:"name,omitempty"`
 	Code        string `url:"code,omitempty"`
@@ -422,7 +422,7 @@ type CustomFieldsFilter struct {
 	DisplayArea string `url:"displayArea,omitempty"`
 }
 
-// CustomDictionariesFilter type
+// CustomDictionariesFilter type.
 type CustomDictionariesFilter struct {
 	Name string `url:"name,omitempty"`
 	Code string `url:"code,omitempty"`
diff --git a/v5/marshaling.go b/v5/marshaling.go
index 6cc65cf..15cfd50 100644
--- a/v5/marshaling.go
+++ b/v5/marshaling.go
@@ -1,7 +1,35 @@
 package v5
 
-import "encoding/json"
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+)
 
 func (t Tag) MarshalJSON() ([]byte, error) {
 	return json.Marshal(t.Name)
 }
+
+func (a *APIErrorsList) UnmarshalJSON(data []byte) error {
+	var i interface{}
+	var m map[string]string
+	if err := json.Unmarshal(data, &i); err != nil {
+		return err
+	}
+
+	switch e := i.(type) {
+	case map[string]interface{}:
+		m = make(map[string]string, len(e))
+		for idx, val := range e {
+			m[idx] = fmt.Sprint(val)
+		}
+	case []interface{}:
+		m = make(map[string]string, len(e))
+		for idx, val := range e {
+			m[strconv.Itoa(idx)] = fmt.Sprint(val)
+		}
+	}
+
+	*a = m
+	return nil
+}
diff --git a/v5/request.go b/v5/request.go
index 87a5582..8899845 100644
--- a/v5/request.go
+++ b/v5/request.go
@@ -1,33 +1,33 @@
 package v5
 
-// CustomerRequest type
+// CustomerRequest type.
 type CustomerRequest struct {
 	By   string `url:"by,omitempty"`
 	Site string `url:"site,omitempty"`
 }
 
-// CustomersRequest type
+// CustomersRequest type.
 type CustomersRequest struct {
 	Filter CustomersFilter `url:"filter,omitempty"`
 	Limit  int             `url:"limit,omitempty"`
 	Page   int             `url:"page,omitempty"`
 }
 
-// CorporateCustomersRequest type
+// CorporateCustomersRequest type.
 type CorporateCustomersRequest struct {
 	Filter CorporateCustomersFilter `url:"filter,omitempty"`
 	Limit  int                      `url:"limit,omitempty"`
 	Page   int                      `url:"page,omitempty"`
 }
 
-// CorporateCustomersNotesRequest type
+// CorporateCustomersNotesRequest type.
 type CorporateCustomersNotesRequest struct {
 	Filter CorporateCustomersNotesFilter `url:"filter,omitempty"`
 	Limit  int                           `url:"limit,omitempty"`
 	Page   int                           `url:"page,omitempty"`
 }
 
-// CorporateCustomerAddressesRequest type
+// CorporateCustomerAddressesRequest type.
 type CorporateCustomerAddressesRequest struct {
 	Filter CorporateCustomerAddressesFilter `url:"filter,omitempty"`
 	By     string                           `url:"by,omitempty"`
@@ -36,7 +36,7 @@ type CorporateCustomerAddressesRequest struct {
 	Page   int                              `url:"page,omitempty"`
 }
 
-// IdentifiersPairRequest type
+// IdentifiersPairRequest type.
 type IdentifiersPairRequest struct {
 	Filter IdentifiersPairFilter `url:"filter,omitempty"`
 	By     string                `url:"by,omitempty"`
@@ -45,135 +45,135 @@ type IdentifiersPairRequest struct {
 	Page   int                   `url:"page,omitempty"`
 }
 
-// CustomersUploadRequest type
+// CustomersUploadRequest type.
 type CustomersUploadRequest struct {
 	Customers []Customer `url:"customers,omitempty,brackets"`
 	Site      string     `url:"site,omitempty"`
 }
 
-// CustomersHistoryRequest type
+// CustomersHistoryRequest type.
 type CustomersHistoryRequest struct {
 	Filter CustomersHistoryFilter `url:"filter,omitempty"`
 	Limit  int                    `url:"limit,omitempty"`
 	Page   int                    `url:"page,omitempty"`
 }
 
-// CorporateCustomersHistoryRequest type
+// CorporateCustomersHistoryRequest type.
 type CorporateCustomersHistoryRequest struct {
 	Filter CorporateCustomersHistoryFilter `url:"filter,omitempty"`
 	Limit  int                             `url:"limit,omitempty"`
 	Page   int                             `url:"page,omitempty"`
 }
 
-// OrderRequest type
+// OrderRequest type.
 type OrderRequest struct {
 	By   string `url:"by,omitempty"`
 	Site string `url:"site,omitempty"`
 }
 
-// OrdersRequest type
+// OrdersRequest type.
 type OrdersRequest struct {
 	Filter OrdersFilter `url:"filter,omitempty"`
 	Limit  int          `url:"limit,omitempty"`
 	Page   int          `url:"page,omitempty"`
 }
 
-// OrdersStatusesRequest type
+// OrdersStatusesRequest type.
 type OrdersStatusesRequest struct {
 	IDs         []int    `url:"ids,omitempty,brackets"`
 	ExternalIDs []string `url:"externalIds,omitempty,brackets"`
 }
 
-// OrdersUploadRequest type
+// OrdersUploadRequest type.
 type OrdersUploadRequest struct {
 	Orders []Order `url:"orders,omitempty,brackets"`
 	Site   string  `url:"site,omitempty"`
 }
 
-// OrdersHistoryRequest type
+// OrdersHistoryRequest type.
 type OrdersHistoryRequest struct {
 	Filter OrdersHistoryFilter `url:"filter,omitempty"`
 	Limit  int                 `url:"limit,omitempty"`
 	Page   int                 `url:"page,omitempty"`
 }
 
-// PacksRequest type
+// PacksRequest type.
 type PacksRequest struct {
 	Filter PacksFilter `url:"filter,omitempty"`
 	Limit  int         `url:"limit,omitempty"`
 	Page   int         `url:"page,omitempty"`
 }
 
-// PacksHistoryRequest type
+// PacksHistoryRequest type.
 type PacksHistoryRequest struct {
 	Filter OrdersHistoryFilter `url:"filter,omitempty"`
 	Limit  int                 `url:"limit,omitempty"`
 	Page   int                 `url:"page,omitempty"`
 }
 
-// UsersRequest type
+// UsersRequest type.
 type UsersRequest struct {
 	Filter UsersFilter `url:"filter,omitempty"`
 	Limit  int         `url:"limit,omitempty"`
 	Page   int         `url:"page,omitempty"`
 }
 
-// UserGroupsRequest type
+// UserGroupsRequest type.
 type UserGroupsRequest struct {
 	Limit int `url:"limit,omitempty"`
 	Page  int `url:"page,omitempty"`
 }
 
-// TasksRequest type
+// TasksRequest type.
 type TasksRequest struct {
 	Filter TasksFilter `url:"filter,omitempty"`
 	Limit  int         `url:"limit,omitempty"`
 	Page   int         `url:"page,omitempty"`
 }
 
-// NotesRequest type
+// NotesRequest type.
 type NotesRequest struct {
 	Filter NotesFilter `url:"filter,omitempty"`
 	Limit  int         `url:"limit,omitempty"`
 	Page   int         `url:"page,omitempty"`
 }
 
-// SegmentsRequest type
+// SegmentsRequest type.
 type SegmentsRequest struct {
 	Filter SegmentsFilter `url:"filter,omitempty"`
 	Limit  int            `url:"limit,omitempty"`
 	Page   int            `url:"page,omitempty"`
 }
 
-// InventoriesRequest type
+// InventoriesRequest type.
 type InventoriesRequest struct {
 	Filter InventoriesFilter `url:"filter,omitempty"`
 	Limit  int               `url:"limit,omitempty"`
 	Page   int               `url:"page,omitempty"`
 }
 
-// ProductsGroupsRequest type
+// ProductsGroupsRequest type.
 type ProductsGroupsRequest struct {
 	Filter ProductsGroupsFilter `url:"filter,omitempty"`
 	Limit  int                  `url:"limit,omitempty"`
 	Page   int                  `url:"page,omitempty"`
 }
 
-// ProductsRequest type
+// ProductsRequest type.
 type ProductsRequest struct {
 	Filter ProductsFilter `url:"filter,omitempty"`
 	Limit  int            `url:"limit,omitempty"`
 	Page   int            `url:"page,omitempty"`
 }
 
-// ProductsPropertiesRequest type
+// ProductsPropertiesRequest type.
 type ProductsPropertiesRequest struct {
 	Filter ProductsPropertiesFilter `url:"filter,omitempty"`
 	Limit  int                      `url:"limit,omitempty"`
 	Page   int                      `url:"page,omitempty"`
 }
 
-// DeliveryTrackingRequest type
+// DeliveryTrackingRequest type.
 type DeliveryTrackingRequest struct {
 	DeliveryID  string                  `json:"deliveryId,omitempty"`
 	TrackNumber string                  `json:"trackNumber,omitempty"`
@@ -181,35 +181,35 @@ type DeliveryTrackingRequest struct {
 	ExtraData   map[string]string       `json:"extraData,omitempty,brackets"`
 }
 
-// DeliveryShipmentsRequest type
+// DeliveryShipmentsRequest type.
 type DeliveryShipmentsRequest struct {
 	Filter ShipmentFilter `url:"filter,omitempty"`
 	Limit  int            `url:"limit,omitempty"`
 	Page   int            `url:"page,omitempty"`
 }
 
-// CostsRequest type
+// CostsRequest type.
 type CostsRequest struct {
 	Filter CostsFilter `url:"filter,omitempty"`
 	Limit  int         `url:"limit,omitempty"`
 	Page   int         `url:"page,omitempty"`
 }
 
-// FilesRequest type
+// FilesRequest type.
 type FilesRequest struct {
 	Filter FilesFilter `url:"filter,omitempty"`
 	Limit  int         `url:"limit,omitempty"`
 	Page   int         `url:"page,omitempty"`
 }
 
-// CustomFieldsRequest type
+// CustomFieldsRequest type.
 type CustomFieldsRequest struct {
 	Filter CustomFieldsFilter `url:"filter,omitempty"`
 	Limit  int                `url:"limit,omitempty"`
 	Page   int                `url:"page,omitempty"`
 }
 
-// CustomDictionariesRequest type
+// CustomDictionariesRequest type.
 type CustomDictionariesRequest struct {
 	Filter CustomDictionariesFilter `url:"filter,omitempty"`
 	Limit  int                      `url:"limit,omitempty"`
diff --git a/v5/response.go b/v5/response.go
index 227fb35..3920682 100644
--- a/v5/response.go
+++ b/v5/response.go
@@ -1,495 +1,495 @@
 package v5
 
-// SuccessfulResponse type
+// SuccessfulResponse type.
 type SuccessfulResponse struct {
 	Success bool `json:"success,omitempty"`
 }
 
-// CreateResponse type
+// CreateResponse type.
 type CreateResponse struct {
 	Success bool `json:"success"`
 	ID      int  `json:"id,omitempty"`
 }
 
-// OrderCreateResponse type
+// OrderCreateResponse type.
 type OrderCreateResponse struct {
 	CreateResponse
 	Order Order `json:"order,omitempty"`
 }
 
-// OperationResponse type
+// OperationResponse type.
 type OperationResponse struct {
 	Success bool              `json:"success"`
-	Errors  map[string]string `json:"errors,omitempty,brackets"`
+	Errors  map[string]string `json:"errors,omitempty"`
 }
 
-// VersionResponse return available API versions
+// VersionResponse return available API versions.
 type VersionResponse struct {
 	Success  bool     `json:"success,omitempty"`
-	Versions []string `json:"versions,brackets,omitempty"`
+	Versions []string `json:"versions,omitempty"`
 }
 
-// CredentialResponse return available API methods
+// CredentialResponse return available API methods.
 type CredentialResponse struct {
 	Success        bool     `json:"success,omitempty"`
-	Credentials    []string `json:"credentials,brackets,omitempty"`
+	Credentials    []string `json:"credentials,omitempty"`
 	SiteAccess     string   `json:"siteAccess,omitempty"`
-	SitesAvailable []string `json:"sitesAvailable,brackets,omitempty"`
+	SitesAvailable []string `json:"sitesAvailable,omitempty"`
 }
 
-// CustomerResponse type
+// CustomerResponse type.
 type CustomerResponse struct {
 	Success  bool      `json:"success"`
-	Customer *Customer `json:"customer,omitempty,brackets"`
+	Customer *Customer `json:"customer,omitempty"`
 }
 
-// CorporateCustomerResponse type
+// CorporateCustomerResponse type.
 type CorporateCustomerResponse struct {
 	Success           bool               `json:"success"`
-	CorporateCustomer *CorporateCustomer `json:"customerCorporate,omitempty,brackets"`
+	CorporateCustomer *CorporateCustomer `json:"customerCorporate,omitempty"`
 }
 
-// CustomersResponse type
+// CustomersResponse type.
 type CustomersResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Customers  []Customer  `json:"customers,omitempty,brackets"`
+	Customers  []Customer  `json:"customers,omitempty"`
 }
 
-// CorporateCustomersResponse type
+// CorporateCustomersResponse type.
 type CorporateCustomersResponse struct {
 	Success            bool                `json:"success"`
 	Pagination         *Pagination         `json:"pagination,omitempty"`
-	CustomersCorporate []CorporateCustomer `json:"customersCorporate,omitempty,brackets"`
+	CustomersCorporate []CorporateCustomer `json:"customersCorporate,omitempty"`
 }
 
-// CorporateCustomersNotesResponse type
+// CorporateCustomersNotesResponse type.
 type CorporateCustomersNotesResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Notes      []Note      `json:"notes,omitempty,brackets"`
+	Notes      []Note      `json:"notes,omitempty"`
 }
 
-// CorporateCustomersAddressesResponse type
+// CorporateCustomersAddressesResponse type.
 type CorporateCustomersAddressesResponse struct {
 	Success   bool                       `json:"success"`
 	Addresses []CorporateCustomerAddress `json:"addresses"`
 }
 
-// CorporateCustomerCompaniesResponse type
+// CorporateCustomerCompaniesResponse type.
 type CorporateCustomerCompaniesResponse struct {
 	Success   bool      `json:"success"`
 	Companies []Company `json:"companies"`
 }
 
-// CorporateCustomerContactsResponse type
+// CorporateCustomerContactsResponse type.
 type CorporateCustomerContactsResponse struct {
 	Success  bool                       `json:"success"`
 	Contacts []CorporateCustomerContact `json:"contacts"`
 }
 
-// CustomerChangeResponse type
+// CustomerChangeResponse type.
 type CustomerChangeResponse struct {
 	Success bool   `json:"success"`
 	ID      int    `json:"id,omitempty"`
 	State   string `json:"state,omitempty"`
 }
 
-// CorporateCustomerChangeResponse type
+// CorporateCustomerChangeResponse type.
 type CorporateCustomerChangeResponse CustomerChangeResponse
 
-// CustomersUploadResponse type
+// CustomersUploadResponse type.
 type CustomersUploadResponse struct {
 	Success           bool              `json:"success"`
-	UploadedCustomers []IdentifiersPair `json:"uploadedCustomers,omitempty,brackets"`
+	UploadedCustomers []IdentifiersPair `json:"uploadedCustomers,omitempty"`
 }
 
-// CorporateCustomersUploadResponse type
+// CorporateCustomersUploadResponse type.
 type CorporateCustomersUploadResponse CustomersUploadResponse
 
-// CustomersHistoryResponse type
+// CustomersHistoryResponse type.
 type CustomersHistoryResponse struct {
 	Success     bool                    `json:"success,omitempty"`
 	GeneratedAt string                  `json:"generatedAt,omitempty"`
-	History     []CustomerHistoryRecord `json:"history,omitempty,brackets"`
+	History     []CustomerHistoryRecord `json:"history,omitempty"`
 	Pagination  *Pagination             `json:"pagination,omitempty"`
 }
 
-// CorporateCustomersHistoryResponse type
+// CorporateCustomersHistoryResponse type.
 type CorporateCustomersHistoryResponse struct {
 	Success     bool                             `json:"success,omitempty"`
 	GeneratedAt string                           `json:"generatedAt,omitempty"`
-	History     []CorporateCustomerHistoryRecord `json:"history,omitempty,brackets"`
+	History     []CorporateCustomerHistoryRecord `json:"history,omitempty"`
 	Pagination  *Pagination                      `json:"pagination,omitempty"`
 }
 
-// OrderResponse type
+// OrderResponse type.
 type OrderResponse struct {
 	Success bool   `json:"success"`
-	Order   *Order `json:"order,omitempty,brackets"`
+	Order   *Order `json:"order,omitempty"`
 }
 
-// OrdersResponse type
+// OrdersResponse type.
 type OrdersResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Orders     []Order     `json:"orders,omitempty,brackets"`
+	Orders     []Order     `json:"orders,omitempty"`
 }
 
-// OrdersStatusesResponse type
+// OrdersStatusesResponse type.
 type OrdersStatusesResponse struct {
 	Success bool           `json:"success"`
 	Orders  []OrdersStatus `json:"orders"`
 }
 
-// OrdersUploadResponse type
+// OrdersUploadResponse type.
 type OrdersUploadResponse struct {
 	Success        bool              `json:"success"`
-	UploadedOrders []IdentifiersPair `json:"uploadedOrders,omitempty,brackets"`
+	UploadedOrders []IdentifiersPair `json:"uploadedOrders,omitempty"`
 }
 
-// OrdersHistoryResponse type
+// OrdersHistoryResponse type.
 type OrdersHistoryResponse struct {
 	Success     bool                  `json:"success,omitempty"`
 	GeneratedAt string                `json:"generatedAt,omitempty"`
-	History     []OrdersHistoryRecord `json:"history,omitempty,brackets"`
+	History     []OrdersHistoryRecord `json:"history,omitempty"`
 	Pagination  *Pagination           `json:"pagination,omitempty"`
 }
 
-// PackResponse type
+// PackResponse type.
 type PackResponse struct {
 	Success bool  `json:"success"`
-	Pack    *Pack `json:"pack,omitempty,brackets"`
+	Pack    *Pack `json:"pack,omitempty"`
 }
 
-// PacksResponse type
+// PacksResponse type.
 type PacksResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Packs      []Pack      `json:"packs,omitempty,brackets"`
+	Packs      []Pack      `json:"packs,omitempty"`
 }
 
-// PacksHistoryResponse type
+// PacksHistoryResponse type.
 type PacksHistoryResponse struct {
 	Success     bool                 `json:"success,omitempty"`
 	GeneratedAt string               `json:"generatedAt,omitempty"`
-	History     []PacksHistoryRecord `json:"history,omitempty,brackets"`
+	History     []PacksHistoryRecord `json:"history,omitempty"`
 	Pagination  *Pagination          `json:"pagination,omitempty"`
 }
 
-// UserResponse type
+// UserResponse type.
 type UserResponse struct {
 	Success bool  `json:"success"`
-	User    *User `json:"user,omitempty,brackets"`
+	User    *User `json:"user,omitempty"`
 }
 
-// UsersResponse type
+// UsersResponse type.
 type UsersResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Users      []User      `json:"users,omitempty,brackets"`
+	Users      []User      `json:"users,omitempty"`
 }
 
-// UserGroupsResponse type
+// UserGroupsResponse type.
 type UserGroupsResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Groups     []UserGroup `json:"groups,omitempty,brackets"`
+	Groups     []UserGroup `json:"groups,omitempty"`
 }
 
-// TaskResponse type
+// TaskResponse type.
 type TaskResponse struct {
 	Success bool  `json:"success"`
-	Task    *Task `json:"task,omitempty,brackets"`
+	Task    *Task `json:"task,omitempty"`
 }
 
-// TasksResponse type
+// TasksResponse type.
 type TasksResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Tasks      []Task      `json:"tasks,omitempty,brackets"`
+	Tasks      []Task      `json:"tasks,omitempty"`
 }
 
-// NotesResponse type
+// NotesResponse type.
 type NotesResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Notes      []Note      `json:"notes,omitempty,brackets"`
+	Notes      []Note      `json:"notes,omitempty"`
 }
 
-// SegmentsResponse type
+// SegmentsResponse type.
 type SegmentsResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Segments   []Segment   `json:"segments,omitempty,brackets"`
+	Segments   []Segment   `json:"segments,omitempty"`
 }
 
-// SettingsResponse type
+// SettingsResponse type.
 type SettingsResponse struct {
-	Success    bool        `json:"success"`
-	Settings   Settings    `json:"settings,omitempty,brackets"`
+	Success  bool     `json:"success"`
+	Settings Settings `json:"settings,omitempty"`
 }
 
-// CountriesResponse type
+// CountriesResponse type.
 type CountriesResponse struct {
 	Success      bool     `json:"success"`
-	CountriesIso []string `json:"countriesIso,omitempty,brackets"`
+	CountriesIso []string `json:"countriesIso,omitempty"`
 }
 
-// CostGroupsResponse type
+// CostGroupsResponse type.
 type CostGroupsResponse struct {
 	Success    bool        `json:"success"`
-	CostGroups []CostGroup `json:"costGroups,omitempty,brackets"`
+	CostGroups []CostGroup `json:"costGroups,omitempty"`
 }
 
-// CostItemsResponse type
+// CostItemsResponse type.
 type CostItemsResponse struct {
 	Success   bool       `json:"success"`
-	CostItems []CostItem `json:"costItems,omitempty,brackets"`
+	CostItems []CostItem `json:"costItems,omitempty"`
 }
 
-// CouriersResponse type
+// CouriersResponse type.
 type CouriersResponse struct {
 	Success  bool      `json:"success"`
-	Couriers []Courier `json:"couriers,omitempty,brackets"`
+	Couriers []Courier `json:"couriers,omitempty"`
 }
 
-// DeliveryServiceResponse type
+// DeliveryServiceResponse type.
 type DeliveryServiceResponse struct {
 	Success          bool                       `json:"success"`
-	DeliveryServices map[string]DeliveryService `json:"deliveryServices,omitempty,brackets"`
+	DeliveryServices map[string]DeliveryService `json:"deliveryServices,omitempty"`
 }
 
-// DeliveryTypesResponse type
+// DeliveryTypesResponse type.
 type DeliveryTypesResponse struct {
 	Success       bool                    `json:"success"`
-	DeliveryTypes map[string]DeliveryType `json:"deliveryTypes,omitempty,brackets"`
+	DeliveryTypes map[string]DeliveryType `json:"deliveryTypes,omitempty"`
 }
 
-// LegalEntitiesResponse type
+// LegalEntitiesResponse type.
 type LegalEntitiesResponse struct {
 	Success       bool          `json:"success"`
-	LegalEntities []LegalEntity `json:"legalEntities,omitempty,brackets"`
+	LegalEntities []LegalEntity `json:"legalEntities,omitempty"`
 }
 
-// OrderMethodsResponse type
+// OrderMethodsResponse type.
 type OrderMethodsResponse struct {
 	Success      bool                   `json:"success"`
-	OrderMethods map[string]OrderMethod `json:"orderMethods,omitempty,brackets"`
+	OrderMethods map[string]OrderMethod `json:"orderMethods,omitempty"`
 }
 
-// OrderTypesResponse type
+// OrderTypesResponse type.
 type OrderTypesResponse struct {
 	Success    bool                 `json:"success"`
-	OrderTypes map[string]OrderType `json:"orderTypes,omitempty,brackets"`
+	OrderTypes map[string]OrderType `json:"orderTypes,omitempty"`
 }
 
-// PaymentStatusesResponse type
+// PaymentStatusesResponse type.
 type PaymentStatusesResponse struct {
 	Success         bool                     `json:"success"`
-	PaymentStatuses map[string]PaymentStatus `json:"paymentStatuses,omitempty,brackets"`
+	PaymentStatuses map[string]PaymentStatus `json:"paymentStatuses,omitempty"`
 }
 
-// PaymentTypesResponse type
+// PaymentTypesResponse type.
 type PaymentTypesResponse struct {
 	Success      bool                   `json:"success"`
-	PaymentTypes map[string]PaymentType `json:"paymentTypes,omitempty,brackets"`
+	PaymentTypes map[string]PaymentType `json:"paymentTypes,omitempty"`
 }
 
-// PriceTypesResponse type
+// PriceTypesResponse type.
 type PriceTypesResponse struct {
 	Success    bool        `json:"success"`
-	PriceTypes []PriceType `json:"priceTypes,omitempty,brackets"`
+	PriceTypes []PriceType `json:"priceTypes,omitempty"`
 }
 
-// ProductStatusesResponse type
+// ProductStatusesResponse type.
 type ProductStatusesResponse struct {
 	Success         bool                     `json:"success"`
-	ProductStatuses map[string]ProductStatus `json:"productStatuses,omitempty,brackets"`
+	ProductStatuses map[string]ProductStatus `json:"productStatuses,omitempty"`
 }
 
-// StatusesResponse type
+// StatusesResponse type.
 type StatusesResponse struct {
 	Success  bool              `json:"success"`
-	Statuses map[string]Status `json:"statuses,omitempty,brackets"`
+	Statuses map[string]Status `json:"statuses,omitempty"`
 }
 
-// StatusGroupsResponse type
+// StatusGroupsResponse type.
 type StatusGroupsResponse struct {
 	Success      bool                   `json:"success"`
-	StatusGroups map[string]StatusGroup `json:"statusGroups,omitempty,brackets"`
+	StatusGroups map[string]StatusGroup `json:"statusGroups,omitempty"`
 }
 
-// SitesResponse type
+// SitesResponse type.
 type SitesResponse struct {
 	Success bool            `json:"success"`
-	Sites   map[string]Site `json:"sites,omitempty,brackets"`
+	Sites   map[string]Site `json:"sites,omitempty"`
 }
 
-// StoresResponse type
+// StoresResponse type.
 type StoresResponse struct {
 	Success bool    `json:"success"`
-	Stores  []Store `json:"stores,omitempty,brackets"`
+	Stores  []Store `json:"stores,omitempty"`
 }
 
-// InventoriesResponse type
+// InventoriesResponse type.
 type InventoriesResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
 	Offers     []Offer     `json:"offers,omitempty"`
 }
 
-// StoreUploadResponse type
+// StoreUploadResponse type.
 type StoreUploadResponse struct {
 	Success              bool    `json:"success"`
 	ProcessedOffersCount int     `json:"processedOffersCount,omitempty"`
 	NotFoundOffers       []Offer `json:"notFoundOffers,omitempty"`
 }
 
-// ProductsGroupsResponse type
+// ProductsGroupsResponse type.
 type ProductsGroupsResponse struct {
 	Success      bool           `json:"success"`
 	Pagination   *Pagination    `json:"pagination,omitempty"`
-	ProductGroup []ProductGroup `json:"productGroup,omitempty,brackets"`
+	ProductGroup []ProductGroup `json:"productGroup,omitempty"`
 }
 
-// ProductsResponse type
+// ProductsResponse type.
 type ProductsResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Products   []Product   `json:"products,omitempty,brackets"`
+	Products   []Product   `json:"products,omitempty"`
 }
 
-// ProductsPropertiesResponse type
+// ProductsPropertiesResponse type.
 type ProductsPropertiesResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Properties []Property  `json:"properties,omitempty,brackets"`
+	Properties []Property  `json:"properties,omitempty"`
 }
 
-// DeliveryShipmentsResponse type
+// DeliveryShipmentsResponse type.
 type DeliveryShipmentsResponse struct {
 	Success           bool               `json:"success"`
 	Pagination        *Pagination        `json:"pagination,omitempty"`
-	DeliveryShipments []DeliveryShipment `json:"deliveryShipments,omitempty,brackets"`
+	DeliveryShipments []DeliveryShipment `json:"deliveryShipments,omitempty"`
 }
 
-// DeliveryShipmentResponse type
+// DeliveryShipmentResponse type.
 type DeliveryShipmentResponse struct {
 	Success          bool              `json:"success"`
-	DeliveryShipment *DeliveryShipment `json:"deliveryShipment,omitempty,brackets"`
+	DeliveryShipment *DeliveryShipment `json:"deliveryShipment,omitempty"`
 }
 
-// DeliveryShipmentUpdateResponse type
+// DeliveryShipmentUpdateResponse type.
 type DeliveryShipmentUpdateResponse struct {
 	Success bool   `json:"success"`
 	ID      int    `json:"id,omitempty"`
 	Status  string `json:"status,omitempty"`
 }
 
-// IntegrationModuleResponse type
+// IntegrationModuleResponse type.
 type IntegrationModuleResponse struct {
 	Success           bool               `json:"success"`
 	IntegrationModule *IntegrationModule `json:"integrationModule,omitempty"`
 }
 
-// IntegrationModuleEditResponse type
+// IntegrationModuleEditResponse type.
 type IntegrationModuleEditResponse struct {
 	Success bool         `json:"success"`
-	Info    ResponseInfo `json:"info,omitempty,brackets"`
+	Info    ResponseInfo `json:"info,omitempty"`
 }
 
-// ResponseInfo type
+// ResponseInfo type.
 type ResponseInfo struct {
-	MgTransportInfo MgInfo `json:"mgTransport,omitempty,brackets"`
-	MgBotInfo       MgInfo `json:"mgBot,omitempty,brackets"`
+	MgTransportInfo MgInfo `json:"mgTransport,omitempty"`
+	MgBotInfo       MgInfo `json:"mgBot,omitempty"`
 }
 
-// MgInfo type
+// MgInfo type.
 type MgInfo struct {
 	EndpointUrl string `json:"endpointUrl"`
 	Token       string `json:"token"`
 }
 
-// CostsResponse type
+// CostsResponse type.
 type CostsResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
-	Costs      []Cost      `json:"costs,omitempty,brackets"`
+	Costs      []Cost      `json:"costs,omitempty"`
 }
 
-// CostsUploadResponse type
+// CostsUploadResponse type.
 type CostsUploadResponse struct {
 	Success       bool  `json:"success"`
-	UploadedCosts []int `json:"uploadedCosts,omitempty,brackets"`
+	UploadedCosts []int `json:"uploadedCosts,omitempty"`
 }
 
-// CostsDeleteResponse type
+// CostsDeleteResponse type.
 type CostsDeleteResponse struct {
 	Success       bool  `json:"success"`
-	Count         int   `json:"count,omitempty,brackets"`
-	NotRemovedIds []int `json:"notRemovedIds,omitempty,brackets"`
+	Count         int   `json:"count,omitempty"`
+	NotRemovedIds []int `json:"notRemovedIds,omitempty"`
 }
 
-// CostResponse type
+// CostResponse type.
 type CostResponse struct {
 	Success bool  `json:"success"`
-	Cost    *Cost `json:"cost,omitempty,brackets"`
+	Cost    *Cost `json:"cost,omitempty"`
 }
 
-// FilesResponse type
+// FilesResponse type.
 type FilesResponse struct {
 	Success    bool        `json:"success"`
 	Pagination *Pagination `json:"pagination,omitempty"`
 	Files      []File      `json:"files,omitempty"`
 }
 
-// FileUpload response
+// FileUpload response.
 type FileUploadResponse struct {
 	Success bool  `json:"success"`
 	File    *File `json:"file,omitempty"`
 }
 
-// FileResponse type
+// FileResponse type.
 type FileResponse struct {
 	Success bool  `json:"success"`
 	File    *File `json:"file,omitempty"`
 }
 
-// CustomFieldsResponse type
+// CustomFieldsResponse type.
 type CustomFieldsResponse struct {
 	Success      bool           `json:"success"`
 	Pagination   *Pagination    `json:"pagination,omitempty"`
-	CustomFields []CustomFields `json:"customFields,omitempty,brackets"`
+	CustomFields []CustomFields `json:"customFields,omitempty"`
 }
 
-// CustomDictionariesResponse type
+// CustomDictionariesResponse type.
 type CustomDictionariesResponse struct {
 	Success            bool                `json:"success"`
 	Pagination         *Pagination         `json:"pagination,omitempty"`
-	CustomDictionaries *[]CustomDictionary `json:"customDictionaries,omitempty,brackets"`
+	CustomDictionaries *[]CustomDictionary `json:"customDictionaries,omitempty"`
 }
 
-// CustomResponse type
+// CustomResponse type.
 type CustomResponse struct {
 	Success bool   `json:"success"`
 	Code    string `json:"code,omitempty"`
 }
 
-// CustomDictionaryResponse type
+// CustomDictionaryResponse type.
 type CustomDictionaryResponse struct {
 	Success          bool              `json:"success"`
-	CustomDictionary *CustomDictionary `json:"CustomDictionary,omitempty,brackets"`
+	CustomDictionary *CustomDictionary `json:"CustomDictionary,omitempty"`
 }
 
-// CustomFieldResponse type
+// CustomFieldResponse type.
 type CustomFieldResponse struct {
 	Success     bool         `json:"success"`
-	CustomField CustomFields `json:"customField,omitempty,brackets"`
+	CustomField CustomFields `json:"customField,omitempty"`
 }
 
-// UnitsResponse type
+// UnitsResponse type.
 type UnitsResponse struct {
 	Success bool    `json:"success"`
-	Units   *[]Unit `json:"units,omitempty,brackets"`
+	Units   *[]Unit `json:"units,omitempty"`
 }
diff --git a/v5/types.go b/v5/types.go
index 744fdba..c6c4c1a 100644
--- a/v5/types.go
+++ b/v5/types.go
@@ -7,13 +7,13 @@ import (
 	"strings"
 )
 
-// ByID is "id" constant to use as `by` property in methods
+// ByID is "id" constant to use as `by` property in methods.
 const ByID = "id"
 
-// ByExternalId is "externalId" constant to use as `by` property in methods
+// ByExternalId is "externalId" constant to use as `by` property in methods.
 const ByExternalID = "externalId"
 
-// Client type
+// Client type.
 type Client struct {
 	URL        string
 	Key        string
@@ -21,7 +21,7 @@ type Client struct {
 	httpClient *http.Client
 }
 
-// Pagination type
+// Pagination type.
 type Pagination struct {
 	Limit          int `json:"limit,omitempty"`
 	TotalCount     int `json:"totalCount,omitempty"`
@@ -29,7 +29,7 @@ type Pagination struct {
 	TotalPageCount int `json:"totalPageCount,omitempty"`
 }
 
-// Address type
+// Address type.
 type Address struct {
 	Index      string `json:"index,omitempty"`
 	CountryIso string `json:"countryIso,omitempty"`
@@ -51,7 +51,7 @@ type Address struct {
 	Text       string `json:"text,omitempty"`
 }
 
-// GeoHierarchyRow type
+// GeoHierarchyRow type.
 type GeoHierarchyRow struct {
 	Country  string `json:"country,omitempty"`
 	Region   string `json:"region,omitempty"`
@@ -60,7 +60,7 @@ type GeoHierarchyRow struct {
 	CityID   int    `json:"cityId,omitempty"`
 }
 
-// Source type
+// Source type.
 type Source struct {
 	Source   string `json:"source,omitempty"`
 	Medium   string `json:"medium,omitempty"`
@@ -69,7 +69,7 @@ type Source struct {
 	Content  string `json:"content,omitempty"`
 }
 
-// Contragent type
+// Contragent type.
 type Contragent struct {
 	ContragentType    string `json:"contragentType,omitempty"`
 	LegalName         string `json:"legalName,omitempty"`
@@ -88,26 +88,26 @@ type Contragent struct {
 	BankAccount       string `json:"bankAccount,omitempty"`
 }
 
-// APIKey type
+// APIKey type.
 type APIKey struct {
 	Current bool `json:"current,omitempty"`
 }
 
-// Property type
+// Property type.
 type Property struct {
 	Code  string   `json:"code,omitempty"`
 	Name  string   `json:"name,omitempty"`
 	Value string   `json:"value,omitempty"`
-	Sites []string `json:"Sites,omitempty,brackets"`
+	Sites []string `json:"Sites,omitempty"`
 }
 
-// IdentifiersPair type
+// IdentifiersPair type.
 type IdentifiersPair struct {
 	ID         int    `json:"id,omitempty"`
 	ExternalID string `json:"externalId,omitempty"`
 }
 
-// DeliveryTime type
+// DeliveryTime type.
 type DeliveryTime struct {
 	From   string `json:"from,omitempty"`
 	To     string `json:"to,omitempty"`
@@ -118,7 +118,7 @@ type DeliveryTime struct {
 Customer related types
 */
 
-// Customer type
+// Customer type.
 type Customer struct {
 	ID                           int               `json:"id,omitempty"`
 	ExternalID                   string            `json:"externalId,omitempty"`
@@ -127,7 +127,7 @@ type Customer struct {
 	Patronymic                   string            `json:"patronymic,omitempty"`
 	Sex                          string            `json:"sex,omitempty"`
 	Email                        string            `json:"email,omitempty"`
-	Phones                       []Phone           `json:"phones,brackets,omitempty"`
+	Phones                       []Phone           `json:"phones,omitempty"`
 	Address                      *Address          `json:"address,omitempty"`
 	CreatedAt                    string            `json:"createdAt,omitempty"`
 	Birthday                     string            `json:"birthday,omitempty"`
@@ -153,11 +153,11 @@ type Customer struct {
 	BrowserID                    string            `json:"browserId,omitempty"`
 	MgCustomerID                 string            `json:"mgCustomerId,omitempty"`
 	PhotoURL                     string            `json:"photoUrl,omitempty"`
-	CustomFields                 map[string]string `json:"customFields,omitempty,brackets"`
-	Tags                         []Tag             `json:"tags,brackets,omitempty"`
+	CustomFields                 map[string]string `json:"customFields,omitempty"`
+	Tags                         []Tag             `json:"tags,omitempty"`
 }
 
-// CorporateCustomer type
+// CorporateCustomer type.
 type CorporateCustomer struct {
 	ID                 int                        `json:"id,omitempty"`
 	ExternalID         string                     `json:"externalId,omitempty"`
@@ -165,7 +165,7 @@ type CorporateCustomer struct {
 	CreatedAt          string                     `json:"createdAt,omitempty"`
 	Vip                bool                       `json:"vip,omitempty"`
 	Bad                bool                       `json:"bad,omitempty"`
-	CustomFields       map[string]string          `json:"customFields,omitempty,brackets"`
+	CustomFields       map[string]string          `json:"customFields,omitempty"`
 	PersonalDiscount   float32                    `json:"personalDiscount,omitempty"`
 	DiscountCardNumber string                     `json:"discountCardNumber,omitempty"`
 	ManagerID          int                        `json:"managerId,omitempty"`
@@ -226,22 +226,22 @@ type Company struct {
 	CreatedAt    string            `json:"createdAt,omitempty"`
 	Contragent   *Contragent       `json:"contragent,omitempty"`
 	Address      *IdentifiersPair  `json:"address,omitempty"`
-	CustomFields map[string]string `json:"customFields,omitempty,brackets"`
+	CustomFields map[string]string `json:"customFields,omitempty"`
 }
 
-// CorporateCustomerNote type
+// CorporateCustomerNote type.
 type CorporateCustomerNote struct {
 	ManagerID int              `json:"managerId,omitempty"`
 	Text      string           `json:"text,omitempty"`
 	Customer  *IdentifiersPair `json:"customer,omitempty"`
 }
 
-// Phone type
+// Phone type.
 type Phone struct {
 	Number string `json:"number,omitempty"`
 }
 
-// CustomerHistoryRecord type
+// CustomerHistoryRecord type.
 type CustomerHistoryRecord struct {
 	ID        int       `json:"id,omitempty"`
 	CreatedAt string    `json:"createdAt,omitempty"`
@@ -249,12 +249,12 @@ type CustomerHistoryRecord struct {
 	Deleted   bool      `json:"deleted,omitempty"`
 	Source    string    `json:"source,omitempty"`
 	Field     string    `json:"field,omitempty"`
-	User      *User     `json:"user,omitempty,brackets"`
-	APIKey    *APIKey   `json:"apiKey,omitempty,brackets"`
-	Customer  *Customer `json:"customer,omitempty,brackets"`
+	User      *User     `json:"user,omitempty"`
+	APIKey    *APIKey   `json:"apiKey,omitempty"`
+	Customer  *Customer `json:"customer,omitempty"`
 }
 
-// CorporateCustomerHistoryRecord type
+// CorporateCustomerHistoryRecord type.
 type CorporateCustomerHistoryRecord struct {
 	ID                int                `json:"id,omitempty"`
 	CreatedAt         string             `json:"createdAt,omitempty"`
@@ -262,16 +262,16 @@ type CorporateCustomerHistoryRecord struct {
 	Deleted           bool               `json:"deleted,omitempty"`
 	Source            string             `json:"source,omitempty"`
 	Field             string             `json:"field,omitempty"`
-	User              *User              `json:"user,omitempty,brackets"`
-	APIKey            *APIKey            `json:"apiKey,omitempty,brackets"`
-	CorporateCustomer *CorporateCustomer `json:"corporateCustomer,omitempty,brackets"`
+	User              *User              `json:"user,omitempty"`
+	APIKey            *APIKey            `json:"apiKey,omitempty"`
+	CorporateCustomer *CorporateCustomer `json:"corporateCustomer,omitempty"`
 }
 
 /**
 Order related types
 */
 
-// Order type
+// Order type.
 type Order struct {
 	ID                            int                     `json:"id,omitempty"`
 	ExternalID                    string                  `json:"externalId,omitempty"`
@@ -319,12 +319,12 @@ type Order struct {
 	Customer                      *Customer               `json:"customer,omitempty"`
 	Delivery                      *OrderDelivery          `json:"delivery,omitempty"`
 	Marketplace                   *OrderMarketplace       `json:"marketplace,omitempty"`
-	Items                         []OrderItem             `json:"items,omitempty,brackets"`
-	CustomFields                  map[string]string       `json:"customFields,omitempty,brackets"`
-	Payments                      map[string]OrderPayment `json:"payments,omitempty,brackets"`
+	Items                         []OrderItem             `json:"items,omitempty"`
+	CustomFields                  map[string]string       `json:"customFields,omitempty"`
+	Payments                      map[string]OrderPayment `json:"payments,omitempty"`
 }
 
-// OrdersStatus type
+// OrdersStatus type.
 type OrdersStatus struct {
 	ID         int    `json:"id"`
 	ExternalID string `json:"externalId,omitempty"`
@@ -332,7 +332,7 @@ type OrdersStatus struct {
 	Group      string `json:"group"`
 }
 
-// OrderDelivery type
+// OrderDelivery type.
 type OrderDelivery struct {
 	Code            string                `json:"code,omitempty"`
 	IntegrationCode string                `json:"integrationCode,omitempty"`
@@ -346,21 +346,21 @@ type OrderDelivery struct {
 	Data            *OrderDeliveryData    `json:"data,omitempty"`
 }
 
-// OrderDeliveryTime type
+// OrderDeliveryTime type.
 type OrderDeliveryTime struct {
 	From   string `json:"from,omitempty"`
 	To     string `json:"to,omitempty"`
 	Custom string `json:"custom,omitempty"`
 }
 
-// OrderDeliveryService type
+// OrderDeliveryService type.
 type OrderDeliveryService struct {
 	Name   string `json:"name,omitempty"`
 	Code   string `json:"code,omitempty"`
 	Active bool   `json:"active,omitempty"`
 }
 
-// OrderDeliveryDataBasic type
+// OrderDeliveryDataBasic type.
 type OrderDeliveryDataBasic struct {
 	TrackNumber        string `json:"trackNumber,omitempty"`
 	Status             string `json:"status,omitempty"`
@@ -368,13 +368,13 @@ type OrderDeliveryDataBasic struct {
 	PayerType          string `json:"payerType,omitempty"`
 }
 
-// OrderDeliveryData type
+// OrderDeliveryData type.
 type OrderDeliveryData struct {
 	OrderDeliveryDataBasic
 	AdditionalFields map[string]interface{}
 }
 
-// UnmarshalJSON method
+// UnmarshalJSON method.
 func (v *OrderDeliveryData) UnmarshalJSON(b []byte) error {
 	var additionalData map[string]interface{}
 	json.Unmarshal(b, &additionalData)
@@ -396,7 +396,7 @@ func (v *OrderDeliveryData) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-// MarshalJSON method
+// MarshalJSON method.
 func (v OrderDeliveryData) MarshalJSON() ([]byte, error) {
 	result := map[string]interface{}{}
 	data, _ := json.Marshal(v.OrderDeliveryDataBasic)
@@ -409,13 +409,13 @@ func (v OrderDeliveryData) MarshalJSON() ([]byte, error) {
 	return json.Marshal(result)
 }
 
-// OrderMarketplace type
+// OrderMarketplace type.
 type OrderMarketplace struct {
 	Code    string `json:"code,omitempty"`
 	OrderID string `json:"orderId,omitempty"`
 }
 
-// OrderPayment type
+// OrderPayment type.
 type OrderPayment struct {
 	ID         int     `json:"id,omitempty"`
 	ExternalID string  `json:"externalId,omitempty"`
@@ -426,7 +426,7 @@ type OrderPayment struct {
 	Comment    string  `json:"comment,omitempty"`
 }
 
-// OrderItem type
+// OrderItem type.
 type OrderItem struct {
 	ID                    int                 `json:"id,omitempty"`
 	InitialPrice          float32             `json:"initialPrice,omitempty"`
@@ -442,11 +442,11 @@ type OrderItem struct {
 	Comment               string              `json:"comment,omitempty"`
 	IsCanceled            bool                `json:"isCanceled,omitempty"`
 	Offer                 Offer               `json:"offer,omitempty"`
-	Properties            map[string]Property `json:"properties,omitempty,brackets"`
+	Properties            map[string]Property `json:"properties,omitempty"`
 	PriceType             *PriceType          `json:"priceType,omitempty"`
 }
 
-// OrdersHistoryRecord type
+// OrdersHistoryRecord type.
 type OrdersHistoryRecord struct {
 	ID        int     `json:"id,omitempty"`
 	CreatedAt string  `json:"createdAt,omitempty"`
@@ -454,12 +454,12 @@ type OrdersHistoryRecord struct {
 	Deleted   bool    `json:"deleted,omitempty"`
 	Source    string  `json:"source,omitempty"`
 	Field     string  `json:"field,omitempty"`
-	User      *User   `json:"user,omitempty,brackets"`
-	APIKey    *APIKey `json:"apiKey,omitempty,brackets"`
-	Order     *Order  `json:"order,omitempty,brackets"`
+	User      *User   `json:"user,omitempty"`
+	APIKey    *APIKey `json:"apiKey,omitempty"`
+	Order     *Order  `json:"order,omitempty"`
 }
 
-// Pack type
+// Pack type.
 type Pack struct {
 	ID                 int       `json:"id,omitempty"`
 	PurchasePrice      float32   `json:"purchasePrice,omitempty"`
@@ -473,14 +473,14 @@ type Pack struct {
 	Unit               *Unit     `json:"unit,omitempty"`
 }
 
-// PackItem type
+// PackItem type.
 type PackItem struct {
 	ID    int    `json:"id,omitempty"`
 	Order *Order `json:"order,omitempty"`
 	Offer *Offer `json:"offer,omitempty"`
 }
 
-// PacksHistoryRecord type
+// PacksHistoryRecord type.
 type PacksHistoryRecord struct {
 	ID        int    `json:"id,omitempty"`
 	CreatedAt string `json:"createdAt,omitempty"`
@@ -488,11 +488,11 @@ type PacksHistoryRecord struct {
 	Deleted   bool   `json:"deleted,omitempty"`
 	Source    string `json:"source,omitempty"`
 	Field     string `json:"field,omitempty"`
-	User      *User  `json:"user,omitempty,brackets"`
-	Pack      *Pack  `json:"pack,omitempty,brackets"`
+	User      *User  `json:"user,omitempty"`
+	Pack      *Pack  `json:"pack,omitempty"`
 }
 
-// Offer type
+// Offer type.
 type Offer struct {
 	ID            int               `json:"id,omitempty"`
 	ExternalID    string            `json:"externalId,omitempty"`
@@ -507,21 +507,21 @@ type Offer struct {
 	Width         float32           `json:"width,omitempty"`
 	Length        float32           `json:"length,omitempty"`
 	Weight        float32           `json:"weight,omitempty"`
-	Stores        []Inventory       `json:"stores,omitempty,brackets"`
-	Properties    map[string]string `json:"properties,omitempty,brackets"`
-	Prices        []OfferPrice      `json:"prices,omitempty,brackets"`
-	Images        []string          `json:"images,omitempty,brackets"`
-	Unit          *Unit             `json:"unit,omitempty,brackets"`
+	Stores        []Inventory       `json:"stores,omitempty"`
+	Properties    map[string]string `json:"properties,omitempty"`
+	Prices        []OfferPrice      `json:"prices,omitempty"`
+	Images        []string          `json:"images,omitempty"`
+	Unit          *Unit             `json:"unit,omitempty"`
 }
 
-// Inventory type
+// Inventory type.
 type Inventory struct {
 	PurchasePrice float32 `json:"purchasePrice,omitempty"`
 	Quantity      float32 `json:"quantity,omitempty"`
 	Store         string  `json:"store,omitempty"`
 }
 
-// InventoryUpload type
+// InventoryUpload type.
 type InventoryUpload struct {
 	ID         int                    `json:"id,omitempty"`
 	ExternalID string                 `json:"externalId,omitempty"`
@@ -529,21 +529,21 @@ type InventoryUpload struct {
 	Stores     []InventoryUploadStore `json:"stores,omitempty"`
 }
 
-// InventoryUploadStore type
+// InventoryUploadStore type.
 type InventoryUploadStore struct {
 	PurchasePrice float32 `json:"purchasePrice,omitempty"`
 	Available     float32 `json:"available,omitempty"`
 	Code          string  `json:"code,omitempty"`
 }
 
-// OfferPrice type
+// OfferPrice type.
 type OfferPrice struct {
 	Price     float32 `json:"price,omitempty"`
 	Ordering  int     `json:"ordering,omitempty"`
 	PriceType string  `json:"priceType,omitempty"`
 }
 
-// OfferPriceUpload type
+// OfferPriceUpload type.
 type OfferPriceUpload struct {
 	ID         int           `json:"id,omitempty"`
 	ExternalID string        `json:"externalId,omitempty"`
@@ -552,13 +552,13 @@ type OfferPriceUpload struct {
 	Prices     []PriceUpload `json:"prices,omitempty"`
 }
 
-// PriceUpload type
+// PriceUpload type.
 type PriceUpload struct {
 	Code  string  `json:"code,omitempty"`
 	Price float32 `json:"price,omitempty"`
 }
 
-// Unit type
+// Unit type.
 type Unit struct {
 	Code    string `json:"code"`
 	Name    string `json:"name"`
@@ -571,7 +571,7 @@ type Unit struct {
 User related types
 */
 
-// User type
+// User type.
 type User struct {
 	ID         int         `json:"id,omitempty"`
 	FirstName  string      `json:"firstName,omitempty"`
@@ -585,30 +585,30 @@ type User struct {
 	Email      string      `json:"email,omitempty"`
 	Phone      string      `json:"phone,omitempty"`
 	Status     string      `json:"status,omitempty"`
-	Groups     []UserGroup `json:"groups,omitempty,brackets"`
+	Groups     []UserGroup `json:"groups,omitempty"`
 	MgUserId   uint64      `json:"mgUserId,omitempty"`
 }
 
-// UserGroup type
+// UserGroup type.
 type UserGroup struct {
 	Name                  string   `json:"name,omitempty"`
 	Code                  string   `json:"code,omitempty"`
 	SignatureTemplate     string   `json:"signatureTemplate,omitempty"`
 	IsManager             bool     `json:"isManager,omitempty"`
 	IsDeliveryMen         bool     `json:"isDeliveryMen,omitempty"`
-	DeliveryTypes         []string `json:"deliveryTypes,omitempty,brackets"`
-	BreakdownOrderTypes   []string `json:"breakdownOrderTypes,omitempty,brackets"`
-	BreakdownSites        []string `json:"breakdownSites,omitempty,brackets"`
-	BreakdownOrderMethods []string `json:"breakdownOrderMethods,omitempty,brackets"`
-	GrantedOrderTypes     []string `json:"grantedOrderTypes,omitempty,brackets"`
-	GrantedSites          []string `json:"grantedSites,omitempty,brackets"`
+	DeliveryTypes         []string `json:"deliveryTypes,omitempty"`
+	BreakdownOrderTypes   []string `json:"breakdownOrderTypes,omitempty"`
+	BreakdownSites        []string `json:"breakdownSites,omitempty"`
+	BreakdownOrderMethods []string `json:"breakdownOrderMethods,omitempty"`
+	GrantedOrderTypes     []string `json:"grantedOrderTypes,omitempty"`
+	GrantedSites          []string `json:"grantedSites,omitempty"`
 }
 
 /**
 Task related types
 */
 
-// Task type
+// Task type.
 type Task struct {
 	ID          int       `json:"id,omitempty"`
 	PerformerID int       `json:"performerId,omitempty"`
@@ -629,7 +629,7 @@ type Task struct {
 	Notes related types
 */
 
-// Note type
+// Note type.
 type Note struct {
 	ID        int       `json:"id,omitempty"`
 	ManagerID int       `json:"managerId,omitempty"`
@@ -642,7 +642,7 @@ type Note struct {
 	Payments related types
 */
 
-// Payment type
+// Payment type.
 type Payment struct {
 	ID         int     `json:"id,omitempty"`
 	ExternalID string  `json:"externalId,omitempty"`
@@ -658,7 +658,7 @@ type Payment struct {
 	Segment related types
 */
 
-// Segment type
+// Segment type.
 type Segment struct {
 	ID             int    `json:"id,omitempty"`
 	Code           string `json:"code,omitempty"`
@@ -690,7 +690,7 @@ type Settings struct {
 Reference related types
 */
 
-// CostGroup type
+// CostGroup type.
 type CostGroup struct {
 	Name     string `json:"name,omitempty"`
 	Code     string `json:"code,omitempty"`
@@ -699,7 +699,7 @@ type CostGroup struct {
 	Ordering int    `json:"ordering,omitempty"`
 }
 
-// CostItem type
+// CostItem type.
 type CostItem struct {
 	Name            string  `json:"name,omitempty"`
 	Code            string  `json:"code,omitempty"`
@@ -712,7 +712,7 @@ type CostItem struct {
 	Source          *Source `json:"source,omitempty"`
 }
 
-// Courier type
+// Courier type.
 type Courier struct {
 	ID          int    `json:"id,omitempty"`
 	FirstName   string `json:"firstName,omitempty"`
@@ -724,14 +724,14 @@ type Courier struct {
 	Phone       *Phone `json:"phone,omitempty"`
 }
 
-// DeliveryService type
+// DeliveryService type.
 type DeliveryService struct {
 	Name   string `json:"name,omitempty"`
 	Code   string `json:"code,omitempty"`
 	Active bool   `json:"active,omitempty"`
 }
 
-// DeliveryType type
+// DeliveryType type.
 type DeliveryType struct {
 	Name             string   `json:"name,omitempty"`
 	Code             string   `json:"code,omitempty"`
@@ -746,7 +746,7 @@ type DeliveryType struct {
 	PaymentTypes     []string `json:"paymentTypes,omitempty"`
 }
 
-// LegalEntity type
+// LegalEntity type.
 type LegalEntity struct {
 	Code              string `json:"code,omitempty"`
 	VatRate           string `json:"vatRate,omitempty"`
@@ -768,7 +768,7 @@ type LegalEntity struct {
 	BankAccount       string `json:"bankAccount,omitempty"`
 }
 
-// OrderMethod type
+// OrderMethod type.
 type OrderMethod struct {
 	Name          string `json:"name,omitempty"`
 	Code          string `json:"code,omitempty"`
@@ -777,7 +777,7 @@ type OrderMethod struct {
 	DefaultForAPI bool   `json:"defaultForApi,omitempty"`
 }
 
-// OrderType type
+// OrderType type.
 type OrderType struct {
 	Name          string `json:"name,omitempty"`
 	Code          string `json:"code,omitempty"`
@@ -786,7 +786,7 @@ type OrderType struct {
 	DefaultForAPI bool   `json:"defaultForApi,omitempty"`
 }
 
-// PaymentStatus type
+// PaymentStatus type.
 type PaymentStatus struct {
 	Name            string   `json:"name,omitempty"`
 	Code            string   `json:"code,omitempty"`
@@ -796,10 +796,10 @@ type PaymentStatus struct {
 	PaymentComplete bool     `json:"paymentComplete,omitempty"`
 	Description     string   `json:"description,omitempty"`
 	Ordering        int      `json:"ordering,omitempty"`
-	PaymentTypes    []string `json:"paymentTypes,omitempty,brackets"`
+	PaymentTypes    []string `json:"paymentTypes,omitempty"`
 }
 
-// PaymentType type
+// PaymentType type.
 type PaymentType struct {
 	Name            string   `json:"name,omitempty"`
 	Code            string   `json:"code,omitempty"`
@@ -807,11 +807,11 @@ type PaymentType struct {
 	DefaultForCRM   bool     `json:"defaultForCrm,omitempty"`
 	DefaultForAPI   bool     `json:"defaultForApi,omitempty"`
 	Description     string   `json:"description,omitempty"`
-	DeliveryTypes   []string `json:"deliveryTypes,omitempty,brackets"`
-	PaymentStatuses []string `json:"PaymentStatuses,omitempty,brackets"`
+	DeliveryTypes   []string `json:"deliveryTypes,omitempty"`
+	PaymentStatuses []string `json:"PaymentStatuses,omitempty"`
 }
 
-// PriceType type
+// PriceType type.
 type PriceType struct {
 	ID               int               `json:"id,omitempty"`
 	Code             string            `json:"code,omitempty"`
@@ -821,11 +821,11 @@ type PriceType struct {
 	Description      string            `json:"description,omitempty"`
 	FilterExpression string            `json:"filterExpression,omitempty"`
 	Ordering         int               `json:"ordering,omitempty"`
-	Groups           []string          `json:"groups,omitempty,brackets"`
-	Geo              []GeoHierarchyRow `json:"geo,omitempty,brackets"`
+	Groups           []string          `json:"groups,omitempty"`
+	Geo              []GeoHierarchyRow `json:"geo,omitempty"`
 }
 
-// ProductStatus type
+// ProductStatus type.
 type ProductStatus struct {
 	Name                        string `json:"name,omitempty"`
 	Code                        string `json:"code,omitempty"`
@@ -837,7 +837,7 @@ type ProductStatus struct {
 	OrderStatusForProductStatus string `json:"orderStatusForProductStatus,omitempty"`
 }
 
-// Status type
+// Status type.
 type Status struct {
 	Name     string `json:"name,omitempty"`
 	Code     string `json:"code,omitempty"`
@@ -846,17 +846,17 @@ type Status struct {
 	Group    string `json:"group,omitempty"`
 }
 
-// StatusGroup type
+// StatusGroup type.
 type StatusGroup struct {
 	Name     string   `json:"name,omitempty"`
 	Code     string   `json:"code,omitempty"`
 	Active   bool     `json:"active,omitempty"`
 	Ordering int      `json:"ordering,omitempty"`
 	Process  bool     `json:"process,omitempty"`
-	Statuses []string `json:"statuses,omitempty,brackets"`
+	Statuses []string `json:"statuses,omitempty"`
 }
 
-// Site type
+// Site type.
 type Site struct {
 	Name             string       `json:"name,omitempty"`
 	Code             string       `json:"code,omitempty"`
@@ -873,7 +873,7 @@ type Site struct {
 	Contragent       *LegalEntity `json:"contragent,omitempty"`
 }
 
-// Store type
+// Store type.
 type Store struct {
 	Name          string   `json:"name,omitempty"`
 	Code          string   `json:"code,omitempty"`
@@ -888,7 +888,7 @@ type Store struct {
 	Address       *Address `json:"address,omitempty"`
 }
 
-// ProductGroup type
+// ProductGroup type.
 type ProductGroup struct {
 	ID       int    `json:"id,omitempty"`
 	ParentID int    `json:"parentId,omitempty"`
@@ -897,7 +897,7 @@ type ProductGroup struct {
 	Active   bool   `json:"active,omitempty"`
 }
 
-// Product type
+// Product type.
 type Product struct {
 	ID           int               `json:"id,omitempty"`
 	MaxPrice     float32           `json:"maxPrice,omitempty"`
@@ -915,19 +915,19 @@ type Product struct {
 	Recommended  bool              `json:"recommended,omitempty"`
 	Active       bool              `json:"active,omitempty"`
 	Quantity     float32           `json:"quantity,omitempty"`
-	Offers       []Offer           `json:"offers,omitempty,brackets"`
-	Groups       []ProductGroup    `json:"groups,omitempty,brackets"`
-	Properties   map[string]string `json:"properties,omitempty,brackets"`
+	Offers       []Offer           `json:"offers,omitempty"`
+	Groups       []ProductGroup    `json:"groups,omitempty"`
+	Properties   map[string]string `json:"properties,omitempty"`
 }
 
-// DeliveryHistoryRecord type
+// DeliveryHistoryRecord type.
 type DeliveryHistoryRecord struct {
 	Code      string `json:"code,omitempty"`
 	UpdatedAt string `json:"updatedAt,omitempty"`
 	Comment   string `json:"comment,omitempty"`
 }
 
-// DeliveryShipment type
+// DeliveryShipment type.
 type DeliveryShipment struct {
 	IntegrationCode string            `json:"integrationCode,omitempty"`
 	ID              int               `json:"id,omitempty"`
@@ -940,11 +940,11 @@ type DeliveryShipment struct {
 	Time            *DeliveryTime     `json:"time,omitempty"`
 	LunchTime       string            `json:"lunchTime,omitempty"`
 	Comment         string            `json:"comment,omitempty"`
-	Orders          []Order           `json:"orders,omitempty,brackets"`
-	ExtraData       map[string]string `json:"extraData,omitempty,brackets"`
+	Orders          []Order           `json:"orders,omitempty"`
+	ExtraData       map[string]string `json:"extraData,omitempty"`
 }
 
-// IntegrationModule type
+// IntegrationModule type.
 type IntegrationModule struct {
 	Code               string            `json:"code,omitempty"`
 	IntegrationCode    string            `json:"integrationCode,omitempty"`
@@ -961,7 +961,7 @@ type IntegrationModule struct {
 	Integrations       *Integrations     `json:"integrations,omitempty"`
 }
 
-// Integrations type
+// Integrations type.
 type Integrations struct {
 	Telephony   *Telephony   `json:"telephony,omitempty"`
 	Delivery    *Delivery    `json:"delivery,omitempty"`
@@ -970,11 +970,11 @@ type Integrations struct {
 	MgBot       *MgBot       `json:"mgBot,omitempty"`
 }
 
-// Delivery type
+// Delivery type.
 type Delivery struct {
 	Description           string              `json:"description,omitempty"`
-	Actions               map[string]string   `json:"actions,omitempty,brackets"`
-	PayerType             []string            `json:"payerType,omitempty,brackets"`
+	Actions               map[string]string   `json:"actions,omitempty"`
+	PayerType             []string            `json:"payerType,omitempty"`
 	PlatePrintLimit       int                 `json:"platePrintLimit,omitempty"`
 	RateDeliveryCost      bool                `json:"rateDeliveryCost,omitempty"`
 	AllowPackages         bool                `json:"allowPackages,omitempty"`
@@ -989,20 +989,20 @@ type Delivery struct {
 	ShipmentDataFieldList []DeliveryDataField `json:"shipmentDataFieldList,omitempty"`
 }
 
-// DeliveryStatus type
+// DeliveryStatus type.
 type DeliveryStatus struct {
 	Code       string `json:"code,omitempty"`
 	Name       string `json:"name,omitempty"`
 	IsEditable bool   `json:"isEditable,omitempty"`
 }
 
-// Plate type
+// Plate type.
 type Plate struct {
 	Code  string `json:"code,omitempty"`
 	Label string `json:"label,omitempty"`
 }
 
-// DeliveryDataField type
+// DeliveryDataField type.
 type DeliveryDataField struct {
 	Code            string `json:"code,omitempty"`
 	Label           string `json:"label,omitempty"`
@@ -1015,7 +1015,7 @@ type DeliveryDataField struct {
 	Editable        bool   `json:"editable,omitempty"`
 }
 
-// Telephony type
+// Telephony type.
 type Telephony struct {
 	MakeCallURL          string           `json:"makeCallUrl,omitempty"`
 	AllowEdit            bool             `json:"allowEdit,omitempty"`
@@ -1023,47 +1023,47 @@ type Telephony struct {
 	OutputEventSupported bool             `json:"outputEventSupported,omitempty"`
 	HangupEventSupported bool             `json:"hangupEventSupported,omitempty"`
 	ChangeUserStatusURL  string           `json:"changeUserStatusUrl,omitempty"`
-	AdditionalCodes      []AdditionalCode `json:"additionalCodes,omitempty,brackets"`
-	ExternalPhones       []ExternalPhone  `json:"externalPhones,omitempty,brackets"`
+	AdditionalCodes      []AdditionalCode `json:"additionalCodes,omitempty"`
+	ExternalPhones       []ExternalPhone  `json:"externalPhones,omitempty"`
 }
 
-// AdditionalCode type
+// AdditionalCode type.
 type AdditionalCode struct {
 	Code   string `json:"code,omitempty"`
 	UserID string `json:"userId,omitempty"`
 }
 
-// ExternalPhone type
+// ExternalPhone type.
 type ExternalPhone struct {
 	SiteCode      string `json:"siteCode,omitempty"`
 	ExternalPhone string `json:"externalPhone,omitempty"`
 }
 
-// Warehouse type
+// Warehouse type.
 type Warehouse struct {
-	Actions []Action `json:"actions,omitempty,brackets"`
+	Actions []Action `json:"actions,omitempty"`
 }
 
-// Action type
+// Action type.
 type Action struct {
 	Code       string   `json:"code,omitempty"`
 	URL        string   `json:"url,omitempty"`
 	CallPoints []string `json:"callPoints,omitempty"`
 }
 
-// MgTransport type
+// MgTransport type.
 type MgTransport struct {
 	WebhookUrl string `json:"webhookUrl,omitempty"`
 }
 
-// MgBot type
+// MgBot type.
 type MgBot struct{}
 
 /**
 Cost related types
 */
 
-// CostRecord type
+// CostRecord type.
 type CostRecord struct {
 	Source   *Source  `json:"source,omitempty"`
 	Comment  string   `json:"comment,omitempty"`
@@ -1073,10 +1073,10 @@ type CostRecord struct {
 	CostItem string   `json:"costItem,omitempty"`
 	UserId   int      `json:"userId,omitempty"`
 	Order    *Order   `json:"order,omitempty"`
-	Sites    []string `json:"sites,omitempty,brackets"`
+	Sites    []string `json:"sites,omitempty"`
 }
 
-// Cost type
+// Cost type.
 type Cost struct {
 	Source    *Source  `json:"source,omitempty"`
 	ID        int      `json:"id,omitempty"`
@@ -1089,10 +1089,10 @@ type Cost struct {
 	CreatedBy string   `json:"createdBy,omitempty"`
 	Order     *Order   `json:"order,omitempty"`
 	UserId    int      `json:"userId,omitempty"`
-	Sites     []string `json:"sites,omitempty,brackets"`
+	Sites     []string `json:"sites,omitempty"`
 }
 
-// File type
+// File type.
 type File struct {
 	ID         int          `json:"id,omitempty"`
 	Filename   string       `json:"filename,omitempty"`
@@ -1102,13 +1102,13 @@ type File struct {
 	Attachment []Attachment `json:"attachment,omitempty"`
 }
 
-// Attachment type
+// Attachment type.
 type Attachment struct {
 	Customer *Customer `json:"customer,omitempty"`
 	Order    *Order    `json:"order,omitempty"`
 }
 
-// CustomFields type
+// CustomFields type.
 type CustomFields struct {
 	Name           string `json:"name,omitempty"`
 	Code           string `json:"code,omitempty"`
@@ -1129,27 +1129,27 @@ type CustomFields struct {
 CustomDictionaries related types
 */
 
-// CustomDictionary type
+// CustomDictionary type.
 type CustomDictionary struct {
 	Name     string    `json:"name,omitempty"`
 	Code     string    `json:"code,omitempty"`
-	Elements []Element `json:"elements,omitempty,brackets"`
+	Elements []Element `json:"elements,omitempty"`
 }
 
-// Element type
+// Element type.
 type Element struct {
 	Name     string `json:"name,omitempty"`
 	Code     string `json:"code,omitempty"`
 	Ordering int    `json:"ordering,omitempty"`
 }
 
-// Activity struct
+// Activity struct.
 type Activity struct {
 	Active bool `json:"active"`
 	Freeze bool `json:"freeze"`
 }
 
-// Tag struct
+// Tag struct.
 type Tag struct {
 	Name     string `json:"name,omitempty"`
 	Color    string `json:"color,omitempty"`