diff --git a/src/Error.php b/src/Error.php
index 6b46c3b..28a46a6 100644
--- a/src/Error.php
+++ b/src/Error.php
@@ -1,207 +1,18 @@
 <?php
 namespace GraphQL;
 
-use GraphQL\Language\Source;
-use GraphQL\Language\SourceLocation;
+trigger_error(
+    'GraphQL\Error was moved to GraphQL\Error\Error and will be deleted on next release',
+    E_USER_DEPRECATED
+);
 
 
 /**
  * Class Error
- * A GraphQLError describes an Error found during the parse, validate, or
- * execute phases of performing a GraphQL operation. In addition to a message
- * and stack trace, it also includes information about the locations in a
- * GraphQL document and/or execution result that correspond to the Error.
  *
+ * @deprecated since 2016-10-21 in favor of GraphQL\Error\Error
  * @package GraphQL
  */
-class Error extends \Exception implements \JsonSerializable
+class Error extends \GraphQL\Error\Error
 {
-    /**
-     * A message describing the Error for debugging purposes.
-     *
-     * @var string
-     */
-    public $message;
-
-    /**
-     * An array of [ line => x, column => y] locations within the source GraphQL document
-     * which correspond to this error.
-     *
-     * Errors during validation often contain multiple locations, for example to
-     * point out two things with the same name. Errors during execution include a
-     * single location, the field which produced the error.
-     *
-     * @var SourceLocation[]
-     */
-    private $locations;
-
-    /**
-     * An array describing the JSON-path into the execution response which
-     * corresponds to this error. Only included for errors during execution.
-     *
-     * @var array
-     */
-    public $path;
-
-    /**
-     * An array of GraphQL AST Nodes corresponding to this error.
-     *
-     * @var array
-     */
-    public $nodes;
-
-    /**
-     * The source GraphQL document corresponding to this error.
-     *
-     * @var Source|null
-     */
-    private $source;
-
-    /**
-     * @var array
-     */
-    private $positions;
-
-    /**
-     * Given an arbitrary Error, presumably thrown while attempting to execute a
-     * GraphQL operation, produce a new GraphQLError aware of the location in the
-     * document responsible for the original Error.
-     *
-     * @param $error
-     * @param array|null $nodes
-     * @param array|null $path
-     * @return Error
-     */
-    public static function createLocatedError($error, $nodes = null, $path = null)
-    {
-        if ($error instanceof self) {
-            return $error;
-        }
-
-        if ($error instanceof \Exception) {
-            $message = $error->getMessage();
-            $previous = $error;
-        } else {
-            $message = (string) $error;
-            $previous = null;
-        }
-
-        return new Error($message, $nodes, null, null, $path, $previous);
-    }
-
-    /**
-     * @param Error $error
-     * @return array
-     */
-    public static function formatError(Error $error)
-    {
-        return $error->toSerializableArray();
-    }
-
-    /**
-     * @param string $message
-     * @param array|null $nodes
-     * @param Source $source
-     * @param array|null $positions
-     * @param array|null $path
-     * @param \Exception $previous
-     */
-    public function __construct($message, $nodes = null, Source $source = null, $positions = null, $path = null, \Exception $previous = null)
-    {
-        parent::__construct($message, 0, $previous);
-
-        if ($nodes instanceof \Traversable) {
-            $nodes = iterator_to_array($nodes);
-        }
-
-        $this->nodes = $nodes;
-        $this->source = $source;
-        $this->positions = $positions;
-        $this->path = $path;
-    }
-
-    /**
-     * @return Source|null
-     */
-    public function getSource()
-    {
-        if (null === $this->source) {
-            if (!empty($this->nodes[0]) && !empty($this->nodes[0]->loc)) {
-                $this->source = $this->nodes[0]->loc->source;
-            }
-        }
-        return $this->source;
-    }
-
-    /**
-     * @return array
-     */
-    public function getPositions()
-    {
-        if (null === $this->positions) {
-            if (!empty($this->nodes)) {
-                $positions = array_map(function($node) { return isset($node->loc) ? $node->loc->start : null; }, $this->nodes);
-                $this->positions = array_filter($positions, function($p) {return $p !== null;});
-            }
-        }
-        return $this->positions;
-    }
-
-    /**
-     * @return SourceLocation[]
-     */
-    public function getLocations()
-    {
-        if (null === $this->locations) {
-            $positions = $this->getPositions();
-            $source = $this->getSource();
-
-            if ($positions && $source) {
-                $this->locations = array_map(function ($pos) use ($source) {
-                    return $source->getLocation($pos);
-                }, $positions);
-            } else {
-                $this->locations = [];
-            }
-        }
-
-        return $this->locations;
-    }
-
-    /**
-     * Returns array representation of error suitable for serialization
-     *
-     * @return array
-     */
-    public function toSerializableArray()
-    {
-        $arr = [
-            'message' => $this->getMessage(),
-        ];
-
-        $locations = Utils::map($this->getLocations(), function(SourceLocation $loc) {
-            return $loc->toSerializableArray();
-        });
-
-        if (!empty($locations)) {
-            $arr['locations'] = $locations;
-        }
-        if (!empty($this->path)) {
-            $arr['path'] = $this->path;
-        }
-
-        return $arr;
-    }
-
-    /**
-     * Specify data which should be serialized to JSON
-     * @link http://php.net/manual/en/jsonserializable.jsonserialize.php
-     * @return mixed data which can be serialized by <b>json_encode</b>,
-     * which is a value of any type other than a resource.
-     * @since 5.4.0
-     */
-    function jsonSerialize()
-    {
-        return $this->toSerializableArray();
-    }
 }
diff --git a/src/Error/Error.php b/src/Error/Error.php
new file mode 100644
index 0000000..5976e1c
--- /dev/null
+++ b/src/Error/Error.php
@@ -0,0 +1,208 @@
+<?php
+namespace GraphQL\Error;
+
+use GraphQL\Language\Source;
+use GraphQL\Language\SourceLocation;
+use GraphQL\Utils;
+
+
+/**
+ * Class Error
+ * A GraphQLError describes an Error found during the parse, validate, or
+ * execute phases of performing a GraphQL operation. In addition to a message
+ * and stack trace, it also includes information about the locations in a
+ * GraphQL document and/or execution result that correspond to the Error.
+ *
+ * @package GraphQL
+ */
+class Error extends \Exception implements \JsonSerializable
+{
+    /**
+     * A message describing the Error for debugging purposes.
+     *
+     * @var string
+     */
+    public $message;
+
+    /**
+     * An array of [ line => x, column => y] locations within the source GraphQL document
+     * which correspond to this error.
+     *
+     * Errors during validation often contain multiple locations, for example to
+     * point out two things with the same name. Errors during execution include a
+     * single location, the field which produced the error.
+     *
+     * @var SourceLocation[]
+     */
+    private $locations;
+
+    /**
+     * An array describing the JSON-path into the execution response which
+     * corresponds to this error. Only included for errors during execution.
+     *
+     * @var array
+     */
+    public $path;
+
+    /**
+     * An array of GraphQL AST Nodes corresponding to this error.
+     *
+     * @var array
+     */
+    public $nodes;
+
+    /**
+     * The source GraphQL document corresponding to this error.
+     *
+     * @var Source|null
+     */
+    private $source;
+
+    /**
+     * @var array
+     */
+    private $positions;
+
+    /**
+     * Given an arbitrary Error, presumably thrown while attempting to execute a
+     * GraphQL operation, produce a new GraphQLError aware of the location in the
+     * document responsible for the original Error.
+     *
+     * @param $error
+     * @param array|null $nodes
+     * @param array|null $path
+     * @return Error
+     */
+    public static function createLocatedError($error, $nodes = null, $path = null)
+    {
+        if ($error instanceof self) {
+            return $error;
+        }
+
+        if ($error instanceof \Exception) {
+            $message = $error->getMessage();
+            $previous = $error;
+        } else {
+            $message = (string) $error;
+            $previous = null;
+        }
+
+        return new static($message, $nodes, null, null, $path, $previous);
+    }
+
+    /**
+     * @param Error $error
+     * @return array
+     */
+    public static function formatError(Error $error)
+    {
+        return $error->toSerializableArray();
+    }
+
+    /**
+     * @param string $message
+     * @param array|null $nodes
+     * @param Source $source
+     * @param array|null $positions
+     * @param array|null $path
+     * @param \Exception $previous
+     */
+    public function __construct($message, $nodes = null, Source $source = null, $positions = null, $path = null, \Exception $previous = null)
+    {
+        parent::__construct($message, 0, $previous);
+
+        if ($nodes instanceof \Traversable) {
+            $nodes = iterator_to_array($nodes);
+        }
+
+        $this->nodes = $nodes;
+        $this->source = $source;
+        $this->positions = $positions;
+        $this->path = $path;
+    }
+
+    /**
+     * @return Source|null
+     */
+    public function getSource()
+    {
+        if (null === $this->source) {
+            if (!empty($this->nodes[0]) && !empty($this->nodes[0]->loc)) {
+                $this->source = $this->nodes[0]->loc->source;
+            }
+        }
+        return $this->source;
+    }
+
+    /**
+     * @return array
+     */
+    public function getPositions()
+    {
+        if (null === $this->positions) {
+            if (!empty($this->nodes)) {
+                $positions = array_map(function($node) { return isset($node->loc) ? $node->loc->start : null; }, $this->nodes);
+                $this->positions = array_filter($positions, function($p) {return $p !== null;});
+            }
+        }
+        return $this->positions;
+    }
+
+    /**
+     * @return SourceLocation[]
+     */
+    public function getLocations()
+    {
+        if (null === $this->locations) {
+            $positions = $this->getPositions();
+            $source = $this->getSource();
+
+            if ($positions && $source) {
+                $this->locations = array_map(function ($pos) use ($source) {
+                    return $source->getLocation($pos);
+                }, $positions);
+            } else {
+                $this->locations = [];
+            }
+        }
+
+        return $this->locations;
+    }
+
+    /**
+     * Returns array representation of error suitable for serialization
+     *
+     * @return array
+     */
+    public function toSerializableArray()
+    {
+        $arr = [
+            'message' => $this->getMessage(),
+        ];
+
+        $locations = Utils::map($this->getLocations(), function(SourceLocation $loc) {
+            return $loc->toSerializableArray();
+        });
+
+        if (!empty($locations)) {
+            $arr['locations'] = $locations;
+        }
+        if (!empty($this->path)) {
+            $arr['path'] = $this->path;
+        }
+
+        return $arr;
+    }
+
+    /**
+     * Specify data which should be serialized to JSON
+     * @link http://php.net/manual/en/jsonserializable.jsonserialize.php
+     * @return mixed data which can be serialized by <b>json_encode</b>,
+     * which is a value of any type other than a resource.
+     * @since 5.4.0
+     */
+    function jsonSerialize()
+    {
+        return $this->toSerializableArray();
+    }
+}
diff --git a/src/Error/FormattedError.php b/src/Error/FormattedError.php
new file mode 100644
index 0000000..7e35fa3
--- /dev/null
+++ b/src/Error/FormattedError.php
@@ -0,0 +1,26 @@
+<?php
+namespace GraphQL\Error;
+
+use GraphQL\Language\SourceLocation;
+
+class FormattedError
+{
+    /**
+     * @deprecated since 2016-10-21
+     * @param $error
+     * @param SourceLocation[] $locations
+     * @return array
+     */
+    public static function create($error, array $locations = [])
+    {
+        $formatted = [
+            'message' => $error
+        ];
+
+        if (!empty($locations)) {
+            $formatted['locations'] = array_map(function($loc) { return $loc->toArray();}, $locations);
+        }
+
+        return $formatted;
+    }
+}
diff --git a/src/Error/SyntaxError.php b/src/Error/SyntaxError.php
new file mode 100644
index 0000000..9fc2820
--- /dev/null
+++ b/src/Error/SyntaxError.php
@@ -0,0 +1,54 @@
+<?php
+namespace GraphQL\Error;
+
+use GraphQL\Language\Source;
+use GraphQL\Language\SourceLocation;
+
+/**
+ * Class SyntaxError
+ * @package GraphQL\Error
+ */
+class SyntaxError extends Error
+{
+    /**
+     * @param Source $source
+     * @param int $position
+     * @param string $description
+     */
+    public function __construct(Source $source, $position, $description)
+    {
+        $location = $source->getLocation($position);
+        $syntaxError =
+            "Syntax Error {$source->name} ({$location->line}:{$location->column}) $description\n\n" .
+            self::highlightSourceAtLocation($source, $location);
+
+        parent::__construct($syntaxError, null, $source, [$position]);
+    }
+
+    /**
+     * @param Source $source
+     * @param SourceLocation $location
+     * @return string
+     */
+    public static function highlightSourceAtLocation(Source $source, SourceLocation $location)
+    {
+        $line = $location->line;
+        $prevLineNum = (string)($line - 1);
+        $lineNum = (string)$line;
+        $nextLineNum = (string)($line + 1);
+        $padLen = mb_strlen($nextLineNum, 'UTF-8');
+
+        $unicodeChars = json_decode('"\u2028\u2029"'); // Quick hack to get js-compatible representation of these chars
+        $lines = preg_split('/\r\n|[\n\r' . $unicodeChars . ']/su', $source->body);
+
+        $lpad = function($len, $str) {
+            return str_pad($str, $len - mb_strlen($str, 'UTF-8') + 1, ' ', STR_PAD_LEFT);
+        };
+
+        return
+            ($line >= 2 ? $lpad($padLen, $prevLineNum) . ': ' . $lines[$line - 2] . "\n" : '') .
+            ($lpad($padLen, $lineNum) . ': ' . $lines[$line - 1] . "\n") .
+            (str_repeat(' ', 1 + $padLen + $location->column) . "^\n") .
+            ($line < count($lines) ? $lpad($padLen, $nextLineNum) . ': ' . $lines[$line] . "\n" : '');
+    }
+}
diff --git a/src/Executor/ExecutionContext.php b/src/Executor/ExecutionContext.php
index 0566582..7aa3a0d 100644
--- a/src/Executor/ExecutionContext.php
+++ b/src/Executor/ExecutionContext.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Executor;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\OperationDefinition;
 use GraphQL\Schema;
 
diff --git a/src/Executor/ExecutionResult.php b/src/Executor/ExecutionResult.php
index 8f78ef3..08ee3a5 100644
--- a/src/Executor/ExecutionResult.php
+++ b/src/Executor/ExecutionResult.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Executor;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 
 class ExecutionResult
 {
@@ -44,7 +44,7 @@ class ExecutionResult
         }
 
         if (!empty($this->errors)) {
-            $result['errors'] = array_map(['GraphQL\Error', 'formatError'], $this->errors);
+            $result['errors'] = array_map(['GraphQL\Error\Error', 'formatError'], $this->errors);
         }
         
         if (!empty($this->extensions)) {
diff --git a/src/Executor/Executor.php b/src/Executor/Executor.php
index 48632af..e6236c0 100644
--- a/src/Executor/Executor.php
+++ b/src/Executor/Executor.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Executor;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Document;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\FragmentDefinition;
diff --git a/src/Executor/Values.php b/src/Executor/Values.php
index 0300cee..b43e82a 100644
--- a/src/Executor/Values.php
+++ b/src/Executor/Values.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Executor;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Argument;
 use GraphQL\Language\AST\VariableDefinition;
 use GraphQL\Language\Printer;
diff --git a/src/FormattedError.php b/src/FormattedError.php
index 934743d..9eda817 100644
--- a/src/FormattedError.php
+++ b/src/FormattedError.php
@@ -1,26 +1,16 @@
 <?php
 namespace GraphQL;
 
-use GraphQL\Language\SourceLocation;
+trigger_error(
+    'GraphQL\FormattedError was moved to GraphQL\Error\FormattedError and will be deleted on next release',
+    E_USER_DEPRECATED
+);
 
-class FormattedError
+/**
+ * Class FormattedError
+ * @deprecated since 2016-10-21 in favor of GraphQL\Error\FormattedError
+ * @package GraphQL
+ */
+class FormattedError extends \GraphQL\Error\FormattedError
 {
-    /**
-     * @deprecated since 2016-10-21
-     * @param $error
-     * @param SourceLocation[] $locations
-     * @return array
-     */
-    public static function create($error, array $locations = [])
-    {
-        $formatted = [
-            'message' => $error
-        ];
-
-        if (!empty($locations)) {
-            $formatted['locations'] = array_map(function($loc) { return $loc->toArray();}, $locations);
-        }
-
-        return $formatted;
-    }
 }
diff --git a/src/GraphQL.php b/src/GraphQL.php
index ea2e291..5ae8733 100644
--- a/src/GraphQL.php
+++ b/src/GraphQL.php
@@ -1,6 +1,7 @@
 <?php
 namespace GraphQL;
 
+use GraphQL\Error\Error;
 use GraphQL\Executor\ExecutionResult;
 use GraphQL\Executor\Executor;
 use GraphQL\Language\AST\Document;
diff --git a/src/Language/Lexer.php b/src/Language/Lexer.php
index 5c4ba33..500f5dc 100644
--- a/src/Language/Lexer.php
+++ b/src/Language/Lexer.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Language;
 
-use GraphQL\SyntaxError;
+use GraphQL\Error\SyntaxError;
 use GraphQL\Utils;
 
 /**
diff --git a/src/Language/Parser.php b/src/Language/Parser.php
index 514eae8..795d9ea 100644
--- a/src/Language/Parser.php
+++ b/src/Language/Parser.php
@@ -41,7 +41,7 @@ use GraphQL\Language\AST\TypeSystemDefinition;
 use GraphQL\Language\AST\UnionTypeDefinition;
 use GraphQL\Language\AST\Variable;
 use GraphQL\Language\AST\VariableDefinition;
-use GraphQL\SyntaxError;
+use GraphQL\Error\SyntaxError;
 
 class Parser
 {
diff --git a/src/SyntaxError.php b/src/SyntaxError.php
index 3e4a3b7..7a393f0 100644
--- a/src/SyntaxError.php
+++ b/src/SyntaxError.php
@@ -1,45 +1,16 @@
 <?php
 namespace GraphQL;
 
-use GraphQL\Language\Source;
-use GraphQL\Language\SourceLocation;
+trigger_error(
+    'GraphQL\SyntaxError was moved to GraphQL\Error\SyntaxError and will be deleted on next release',
+    E_USER_DEPRECATED
+);
 
-class SyntaxError extends Error
+/**
+ * Class SyntaxError
+ * @deprecated since 2016-10-21 in favor of GraphQL\Error\SyntaxError
+ * @package GraphQL
+ */
+class SyntaxError extends \GraphQL\Error\SyntaxError
 {
-    /**
-     * @param Source $source
-     * @param int $position
-     * @param string $description
-     */
-    public function __construct(Source $source, $position, $description)
-    {
-        $location = $source->getLocation($position);
-        $syntaxError =
-            "Syntax Error {$source->name} ({$location->line}:{$location->column}) $description\n\n" .
-            self::highlightSourceAtLocation($source, $location);
-
-        parent::__construct($syntaxError, null, $source, [$position]);
-    }
-
-    public static function highlightSourceAtLocation(Source $source, SourceLocation $location)
-    {
-        $line = $location->line;
-        $prevLineNum = (string)($line - 1);
-        $lineNum = (string)$line;
-        $nextLineNum = (string)($line + 1);
-        $padLen = mb_strlen($nextLineNum, 'UTF-8');
-
-        $unicodeChars = json_decode('"\u2028\u2029"'); // Quick hack to get js-compatible representation of these chars
-        $lines = preg_split('/\r\n|[\n\r' . $unicodeChars . ']/su', $source->body);
-
-        $lpad = function($len, $str) {
-            return str_pad($str, $len - mb_strlen($str, 'UTF-8') + 1, ' ', STR_PAD_LEFT);
-        };
-
-        return
-            ($line >= 2 ? $lpad($padLen, $prevLineNum) . ': ' . $lines[$line - 2] . "\n" : '') .
-            ($lpad($padLen, $lineNum) . ': ' . $lines[$line - 1] . "\n") .
-            (str_repeat(' ', 1 + $padLen + $location->column) . "^\n") .
-            ($line < count($lines) ? $lpad($padLen, $nextLineNum) . ': ' . $lines[$line] . "\n" : '');
-    }
 }
diff --git a/src/Type/Definition/Config.php b/src/Type/Definition/Config.php
index 5dfa56b..dde911e 100644
--- a/src/Type/Definition/Config.php
+++ b/src/Type/Definition/Config.php
@@ -178,9 +178,9 @@ class Config
                         if ($def->flags & self::KEY_AS_NAME) {
                             $arrValue += ['name' => $arrKey];
                         }
-                        self::validateMap($typeName, $arrValue, $def->definition, "$pathStr: $arrKey");
+                        self::validateMap($typeName, $arrValue, $def->definition, "$pathStr:$arrKey");
                     } else {
-                        self::validateEntry($typeName, $arrKey, $arrValue, $def->definition, "$pathStr: $arrKey");
+                        self::validateEntry($typeName, $arrKey, $arrValue, $def->definition, "$pathStr:$arrKey");
                     }
                 }
             } else {
diff --git a/src/Type/SchemaValidator.php b/src/Type/SchemaValidator.php
index a1a45a1..af118b2 100644
--- a/src/Type/SchemaValidator.php
+++ b/src/Type/SchemaValidator.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Type;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Schema;
 use GraphQL\Type\Definition\FieldArgument;
 use GraphQL\Type\Definition\FieldDefinition;
diff --git a/src/Validator/DocumentValidator.php b/src/Validator/DocumentValidator.php
index 6f55e0f..1566344 100644
--- a/src/Validator/DocumentValidator.php
+++ b/src/Validator/DocumentValidator.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\ListValue;
 use GraphQL\Language\AST\Document;
 use GraphQL\Language\AST\FragmentSpread;
diff --git a/src/Validator/Rules/ArgumentsOfCorrectType.php b/src/Validator/Rules/ArgumentsOfCorrectType.php
index 3f55473..b89d26c 100644
--- a/src/Validator/Rules/ArgumentsOfCorrectType.php
+++ b/src/Validator/Rules/ArgumentsOfCorrectType.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Argument;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/DefaultValuesOfCorrectType.php b/src/Validator/Rules/DefaultValuesOfCorrectType.php
index 4bc6785..a6978ed 100644
--- a/src/Validator/Rules/DefaultValuesOfCorrectType.php
+++ b/src/Validator/Rules/DefaultValuesOfCorrectType.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\VariableDefinition;
 use GraphQL\Language\Printer;
diff --git a/src/Validator/Rules/FieldsOnCorrectType.php b/src/Validator/Rules/FieldsOnCorrectType.php
index 9422388..aed5acc 100644
--- a/src/Validator/Rules/FieldsOnCorrectType.php
+++ b/src/Validator/Rules/FieldsOnCorrectType.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\Node;
 use GraphQL\Schema;
diff --git a/src/Validator/Rules/FragmentsOnCompositeTypes.php b/src/Validator/Rules/FragmentsOnCompositeTypes.php
index c9779cd..cdb6502 100644
--- a/src/Validator/Rules/FragmentsOnCompositeTypes.php
+++ b/src/Validator/Rules/FragmentsOnCompositeTypes.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\FragmentDefinition;
 use GraphQL\Language\AST\InlineFragment;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/KnownArgumentNames.php b/src/Validator/Rules/KnownArgumentNames.php
index a6f0ea0..963eda6 100644
--- a/src/Validator/Rules/KnownArgumentNames.php
+++ b/src/Validator/Rules/KnownArgumentNames.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Argument;
 use GraphQL\Language\AST\Node;
 use GraphQL\Utils;
diff --git a/src/Validator/Rules/KnownDirectives.php b/src/Validator/Rules/KnownDirectives.php
index 8c3ad4b..f93103c 100644
--- a/src/Validator/Rules/KnownDirectives.php
+++ b/src/Validator/Rules/KnownDirectives.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Directive;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\FragmentDefinition;
diff --git a/src/Validator/Rules/KnownFragmentNames.php b/src/Validator/Rules/KnownFragmentNames.php
index 6361017..9d238ed 100644
--- a/src/Validator/Rules/KnownFragmentNames.php
+++ b/src/Validator/Rules/KnownFragmentNames.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\FragmentSpread;
 use GraphQL\Language\AST\Node;
 use GraphQL\Validator\ValidationContext;
diff --git a/src/Validator/Rules/KnownTypeNames.php b/src/Validator/Rules/KnownTypeNames.php
index 95f1437..affe328 100644
--- a/src/Validator/Rules/KnownTypeNames.php
+++ b/src/Validator/Rules/KnownTypeNames.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Name;
 use GraphQL\Language\AST\NamedType;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/LoneAnonymousOperation.php b/src/Validator/Rules/LoneAnonymousOperation.php
index ee586b1..df8620f 100644
--- a/src/Validator/Rules/LoneAnonymousOperation.php
+++ b/src/Validator/Rules/LoneAnonymousOperation.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Document;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\OperationDefinition;
diff --git a/src/Validator/Rules/NoFragmentCycles.php b/src/Validator/Rules/NoFragmentCycles.php
index addf8d7..56bc585 100644
--- a/src/Validator/Rules/NoFragmentCycles.php
+++ b/src/Validator/Rules/NoFragmentCycles.php
@@ -9,7 +9,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\FragmentDefinition;
 use GraphQL\Language\AST\FragmentSpread;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/NoUndefinedVariables.php b/src/Validator/Rules/NoUndefinedVariables.php
index 9d7ab5a..66da7d1 100644
--- a/src/Validator/Rules/NoUndefinedVariables.php
+++ b/src/Validator/Rules/NoUndefinedVariables.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\FragmentDefinition;
 use GraphQL\Language\AST\FragmentSpread;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/NoUnusedFragments.php b/src/Validator/Rules/NoUnusedFragments.php
index bf88240..a944da0 100644
--- a/src/Validator/Rules/NoUnusedFragments.php
+++ b/src/Validator/Rules/NoUnusedFragments.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\FragmentDefinition;
 use GraphQL\Language\AST\FragmentSpread;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/NoUnusedVariables.php b/src/Validator/Rules/NoUnusedVariables.php
index cf2fc87..7e9b8d7 100644
--- a/src/Validator/Rules/NoUnusedVariables.php
+++ b/src/Validator/Rules/NoUnusedVariables.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\OperationDefinition;
 use GraphQL\Language\Visitor;
diff --git a/src/Validator/Rules/OverlappingFieldsCanBeMerged.php b/src/Validator/Rules/OverlappingFieldsCanBeMerged.php
index 2878f52..713d7d9 100644
--- a/src/Validator/Rules/OverlappingFieldsCanBeMerged.php
+++ b/src/Validator/Rules/OverlappingFieldsCanBeMerged.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Directive;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\FragmentSpread;
diff --git a/src/Validator/Rules/PossibleFragmentSpreads.php b/src/Validator/Rules/PossibleFragmentSpreads.php
index e51bcbb..7fb8940 100644
--- a/src/Validator/Rules/PossibleFragmentSpreads.php
+++ b/src/Validator/Rules/PossibleFragmentSpreads.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\FragmentSpread;
 use GraphQL\Language\AST\InlineFragment;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/ProvidedNonNullArguments.php b/src/Validator/Rules/ProvidedNonNullArguments.php
index 1cdc7fc..4ea7692 100644
--- a/src/Validator/Rules/ProvidedNonNullArguments.php
+++ b/src/Validator/Rules/ProvidedNonNullArguments.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Directive;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/QueryComplexity.php b/src/Validator/Rules/QueryComplexity.php
index 8edc6ae..75d79d8 100644
--- a/src/Validator/Rules/QueryComplexity.php
+++ b/src/Validator/Rules/QueryComplexity.php
@@ -2,7 +2,7 @@
 
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Executor\Values;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\FragmentSpread;
diff --git a/src/Validator/Rules/QueryDepth.php b/src/Validator/Rules/QueryDepth.php
index 8097052..04f08ad 100644
--- a/src/Validator/Rules/QueryDepth.php
+++ b/src/Validator/Rules/QueryDepth.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\FragmentSpread;
 use GraphQL\Language\AST\InlineFragment;
diff --git a/src/Validator/Rules/ScalarLeafs.php b/src/Validator/Rules/ScalarLeafs.php
index f782af2..cfa73e1 100644
--- a/src/Validator/Rules/ScalarLeafs.php
+++ b/src/Validator/Rules/ScalarLeafs.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Field;
 use GraphQL\Language\AST\Node;
 use GraphQL\Type\Definition\Type;
diff --git a/src/Validator/Rules/UniqueArgumentNames.php b/src/Validator/Rules/UniqueArgumentNames.php
index 375f5ce..09bd622 100644
--- a/src/Validator/Rules/UniqueArgumentNames.php
+++ b/src/Validator/Rules/UniqueArgumentNames.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Argument;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\Visitor;
diff --git a/src/Validator/Rules/UniqueFragmentNames.php b/src/Validator/Rules/UniqueFragmentNames.php
index 300912f..c4457f4 100644
--- a/src/Validator/Rules/UniqueFragmentNames.php
+++ b/src/Validator/Rules/UniqueFragmentNames.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Argument;
 use GraphQL\Language\AST\FragmentDefinition;
 use GraphQL\Language\AST\Node;
diff --git a/src/Validator/Rules/UniqueInputFieldNames.php b/src/Validator/Rules/UniqueInputFieldNames.php
index 263790a..9d7d4c6 100644
--- a/src/Validator/Rules/UniqueInputFieldNames.php
+++ b/src/Validator/Rules/UniqueInputFieldNames.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\ObjectField;
 use GraphQL\Language\Visitor;
diff --git a/src/Validator/Rules/UniqueOperationNames.php b/src/Validator/Rules/UniqueOperationNames.php
index 618bc23..dc63059 100644
--- a/src/Validator/Rules/UniqueOperationNames.php
+++ b/src/Validator/Rules/UniqueOperationNames.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\OperationDefinition;
 use GraphQL\Language\Visitor;
diff --git a/src/Validator/Rules/UniqueVariableNames.php b/src/Validator/Rules/UniqueVariableNames.php
index 469813b..8482e7a 100644
--- a/src/Validator/Rules/UniqueVariableNames.php
+++ b/src/Validator/Rules/UniqueVariableNames.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Validator\Rules;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\VariableDefinition;
 use GraphQL\Validator\ValidationContext;
diff --git a/src/Validator/Rules/VariablesAreInputTypes.php b/src/Validator/Rules/VariablesAreInputTypes.php
index edc8c8f..a454ae8 100644
--- a/src/Validator/Rules/VariablesAreInputTypes.php
+++ b/src/Validator/Rules/VariablesAreInputTypes.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\VariableDefinition;
 use GraphQL\Language\Printer;
diff --git a/src/Validator/Rules/VariablesInAllowedPosition.php b/src/Validator/Rules/VariablesInAllowedPosition.php
index 3d23cc6..78d81a9 100644
--- a/src/Validator/Rules/VariablesInAllowedPosition.php
+++ b/src/Validator/Rules/VariablesInAllowedPosition.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Validator\Rules;
 
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\AST\FragmentSpread;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\OperationDefinition;
diff --git a/src/Validator/ValidationContext.php b/src/Validator/ValidationContext.php
index b8f6312..58f0a6c 100644
--- a/src/Validator/ValidationContext.php
+++ b/src/Validator/ValidationContext.php
@@ -7,7 +7,7 @@ use GraphQL\Language\AST\OperationDefinition;
 use GraphQL\Language\AST\Variable;
 use GraphQL\Language\Visitor;
 use \SplObjectStorage;
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Schema;
 use GraphQL\Language\AST\Document;
 use GraphQL\Language\AST\FragmentDefinition;
diff --git a/tests/ErrorTest.php b/tests/ErrorTest.php
index 1d81fa3..9acfbea 100644
--- a/tests/ErrorTest.php
+++ b/tests/ErrorTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Language\Parser;
 use GraphQL\Language\Source;
 use GraphQL\Language\SourceLocation;
diff --git a/tests/Executor/AbstractTest.php b/tests/Executor/AbstractTest.php
index ea6687c..13df495 100644
--- a/tests/Executor/AbstractTest.php
+++ b/tests/Executor/AbstractTest.php
@@ -5,7 +5,7 @@ require_once __DIR__ . '/TestClasses.php';
 
 use GraphQL\Executor\ExecutionResult;
 use GraphQL\Executor\Executor;
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\GraphQL;
 use GraphQL\Language\Parser;
 use GraphQL\Language\SourceLocation;
diff --git a/tests/Executor/ExecutorTest.php b/tests/Executor/ExecutorTest.php
index bcd6720..66dc95b 100644
--- a/tests/Executor/ExecutorTest.php
+++ b/tests/Executor/ExecutorTest.php
@@ -3,9 +3,9 @@ namespace GraphQL\Tests\Executor;
 
 require_once __DIR__ . '/TestClasses.php';
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Executor\Executor;
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\Parser;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
diff --git a/tests/Executor/ListsTest.php b/tests/Executor/ListsTest.php
index 6ec9a59..1cad0e8 100644
--- a/tests/Executor/ListsTest.php
+++ b/tests/Executor/ListsTest.php
@@ -1,9 +1,9 @@
 <?php
 namespace GraphQL\Tests\Executor;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Executor\Executor;
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\Parser;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
diff --git a/tests/Executor/MutationsTest.php b/tests/Executor/MutationsTest.php
index 07f67be..2dadc7b 100644
--- a/tests/Executor/MutationsTest.php
+++ b/tests/Executor/MutationsTest.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Tests\Executor;
 
 use GraphQL\Executor\Executor;
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\Parser;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
diff --git a/tests/Executor/NonNullTest.php b/tests/Executor/NonNullTest.php
index 74f4604..6bf619d 100644
--- a/tests/Executor/NonNullTest.php
+++ b/tests/Executor/NonNullTest.php
@@ -1,9 +1,9 @@
 <?php
 namespace GraphQL\Tests\Executor;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Executor\Executor;
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\Parser;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
diff --git a/tests/Executor/VariablesTest.php b/tests/Executor/VariablesTest.php
index e12763d..d71f9b7 100644
--- a/tests/Executor/VariablesTest.php
+++ b/tests/Executor/VariablesTest.php
@@ -3,9 +3,9 @@ namespace GraphQL\Tests\Executor;
 
 require_once __DIR__ . '/TestClasses.php';
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\Executor\Executor;
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\Parser;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
diff --git a/tests/Language/LexerTest.php b/tests/Language/LexerTest.php
index 4b2c0b2..4d8d952 100644
--- a/tests/Language/LexerTest.php
+++ b/tests/Language/LexerTest.php
@@ -4,7 +4,7 @@ namespace GraphQL\Tests\Language;
 use GraphQL\Language\Lexer;
 use GraphQL\Language\Source;
 use GraphQL\Language\Token;
-use GraphQL\SyntaxError;
+use GraphQL\Error\SyntaxError;
 use GraphQL\Utils;
 
 class LexerTest extends \PHPUnit_Framework_TestCase
diff --git a/tests/Language/ParserTest.php b/tests/Language/ParserTest.php
index 62791ab..fbc93b3 100644
--- a/tests/Language/ParserTest.php
+++ b/tests/Language/ParserTest.php
@@ -14,7 +14,7 @@ use GraphQL\Language\AST\StringValue;
 use GraphQL\Language\Parser;
 use GraphQL\Language\Source;
 use GraphQL\Language\SourceLocation;
-use GraphQL\SyntaxError;
+use GraphQL\Error\SyntaxError;
 use GraphQL\Utils;
 
 class ParserTest extends \PHPUnit_Framework_TestCase
@@ -96,7 +96,7 @@ fragment MissingOn Type
      */
     public function testDoesNotAcceptFragmentsNamedOn()
     {
-        $this->setExpectedException('GraphQL\SyntaxError', 'Syntax Error GraphQL (1:10) Unexpected Name "on"');
+        $this->setExpectedException('GraphQL\Error\SyntaxError', 'Syntax Error GraphQL (1:10) Unexpected Name "on"');
         Parser::parse('fragment on on on { on }');
     }
 
@@ -105,7 +105,7 @@ fragment MissingOn Type
      */
     public function testDoesNotAcceptFragmentSpreadOfOn()
     {
-        $this->setExpectedException('GraphQL\SyntaxError', 'Syntax Error GraphQL (1:9) Expected Name, found }');
+        $this->setExpectedException('GraphQL\Error\SyntaxError', 'Syntax Error GraphQL (1:9) Expected Name, found }');
         Parser::parse('{ ...on }');
     }
 
@@ -114,7 +114,7 @@ fragment MissingOn Type
      */
     public function testDoesNotAllowNullAsValue()
     {
-        $this->setExpectedException('GraphQL\SyntaxError', 'Syntax Error GraphQL (1:39) Unexpected Name "null"');
+        $this->setExpectedException('GraphQL\Error\SyntaxError', 'Syntax Error GraphQL (1:39) Unexpected Name "null"');
         Parser::parse('{ fieldWithNullableStringInput(input: null) }');
     }
 
diff --git a/tests/Language/SchemaParserTest.php b/tests/Language/SchemaParserTest.php
index 4a5b7d1..2f64594 100644
--- a/tests/Language/SchemaParserTest.php
+++ b/tests/Language/SchemaParserTest.php
@@ -593,7 +593,7 @@ input Hello {
 input Hello {
   world(foo: Int): String
 }';
-        $this->setExpectedException('GraphQL\SyntaxError');
+        $this->setExpectedException('GraphQL\Error\SyntaxError');
         Parser::parse($body);
     }
 
diff --git a/tests/Type/EnumTypeTest.php b/tests/Type/EnumTypeTest.php
index ef32c1c..587f195 100644
--- a/tests/Type/EnumTypeTest.php
+++ b/tests/Type/EnumTypeTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Type;
 
-use GraphQL\Error;
+use GraphQL\Error\Error;
 use GraphQL\GraphQL;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
diff --git a/tests/Type/IntrospectionTest.php b/tests/Type/IntrospectionTest.php
index 8e73ae0..3c10912 100644
--- a/tests/Type/IntrospectionTest.php
+++ b/tests/Type/IntrospectionTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Type;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
 use GraphQL\GraphQL;
diff --git a/tests/Validator/AbstractQuerySecurityTest.php b/tests/Validator/AbstractQuerySecurityTest.php
index 6870441..885fc99 100644
--- a/tests/Validator/AbstractQuerySecurityTest.php
+++ b/tests/Validator/AbstractQuerySecurityTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\Parser;
 use GraphQL\Type\Introspection;
 use GraphQL\Validator\DocumentValidator;
@@ -46,7 +46,7 @@ abstract class AbstractQuerySecurityTest extends \PHPUnit_Framework_TestCase
             [$this->getRule($max)]
         );
 
-        $this->assertEquals($expectedErrors, array_map(['GraphQL\Error', 'formatError'], $errors), $queryString);
+        $this->assertEquals($expectedErrors, array_map(['GraphQL\Error\Error', 'formatError'], $errors), $queryString);
 
         return $errors;
     }
diff --git a/tests/Validator/ArgumentsOfCorrectTypeTest.php b/tests/Validator/ArgumentsOfCorrectTypeTest.php
index f53d14a..e180d71 100644
--- a/tests/Validator/ArgumentsOfCorrectTypeTest.php
+++ b/tests/Validator/ArgumentsOfCorrectTypeTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\ArgumentsOfCorrectType;
 
diff --git a/tests/Validator/DefaultValuesOfCorrectTypeTest.php b/tests/Validator/DefaultValuesOfCorrectTypeTest.php
index a979cdd..21aba50 100644
--- a/tests/Validator/DefaultValuesOfCorrectTypeTest.php
+++ b/tests/Validator/DefaultValuesOfCorrectTypeTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Messages;
 use GraphQL\Validator\Rules\DefaultValuesOfCorrectType;
diff --git a/tests/Validator/FieldsOnCorrectTypeTest.php b/tests/Validator/FieldsOnCorrectTypeTest.php
index 09d4ce8..45b498f 100644
--- a/tests/Validator/FieldsOnCorrectTypeTest.php
+++ b/tests/Validator/FieldsOnCorrectTypeTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Messages;
 use GraphQL\Validator\Rules\FieldsOnCorrectType;
diff --git a/tests/Validator/FragmentsOnCompositeTypesTest.php b/tests/Validator/FragmentsOnCompositeTypesTest.php
index e1ad26e..495f44b 100644
--- a/tests/Validator/FragmentsOnCompositeTypesTest.php
+++ b/tests/Validator/FragmentsOnCompositeTypesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\FragmentsOnCompositeTypes;
 
diff --git a/tests/Validator/KnownArgumentNamesTest.php b/tests/Validator/KnownArgumentNamesTest.php
index dece1a8..80ced66 100644
--- a/tests/Validator/KnownArgumentNamesTest.php
+++ b/tests/Validator/KnownArgumentNamesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\KnownArgumentNames;
 
diff --git a/tests/Validator/KnownDirectivesTest.php b/tests/Validator/KnownDirectivesTest.php
index 990ab30..50fe215 100644
--- a/tests/Validator/KnownDirectivesTest.php
+++ b/tests/Validator/KnownDirectivesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\KnownDirectives;
 
diff --git a/tests/Validator/KnownFragmentNamesTest.php b/tests/Validator/KnownFragmentNamesTest.php
index 36ba408..0a7e434 100644
--- a/tests/Validator/KnownFragmentNamesTest.php
+++ b/tests/Validator/KnownFragmentNamesTest.php
@@ -2,7 +2,7 @@
 namespace GraphQL\Tests\Validator;
 
 use GraphQL\Validator\Rules\KnownFragmentNames;
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 
 class KnownFragmentNamesTest extends TestCase
diff --git a/tests/Validator/KnownTypeNamesTest.php b/tests/Validator/KnownTypeNamesTest.php
index 467b9dc..8bdab66 100644
--- a/tests/Validator/KnownTypeNamesTest.php
+++ b/tests/Validator/KnownTypeNamesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\KnownTypeNames;
 
diff --git a/tests/Validator/LoneAnonymousOperationTest.php b/tests/Validator/LoneAnonymousOperationTest.php
index d0d5e72..584d65e 100644
--- a/tests/Validator/LoneAnonymousOperationTest.php
+++ b/tests/Validator/LoneAnonymousOperationTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\LoneAnonymousOperation;
 
diff --git a/tests/Validator/NoFragmentCyclesTest.php b/tests/Validator/NoFragmentCyclesTest.php
index cfb9aa5..f693d2c 100644
--- a/tests/Validator/NoFragmentCyclesTest.php
+++ b/tests/Validator/NoFragmentCyclesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\NoFragmentCycles;
 
diff --git a/tests/Validator/NoUndefinedVariablesTest.php b/tests/Validator/NoUndefinedVariablesTest.php
index 6bc86a3..24b8a9f 100644
--- a/tests/Validator/NoUndefinedVariablesTest.php
+++ b/tests/Validator/NoUndefinedVariablesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\NoUndefinedVariables;
 
diff --git a/tests/Validator/NoUnusedFragmentsTest.php b/tests/Validator/NoUnusedFragmentsTest.php
index 53d5373..f03b28e 100644
--- a/tests/Validator/NoUnusedFragmentsTest.php
+++ b/tests/Validator/NoUnusedFragmentsTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\NoUnusedFragments;
 
diff --git a/tests/Validator/NoUnusedVariablesTest.php b/tests/Validator/NoUnusedVariablesTest.php
index 773eccf..bbdc0fa 100644
--- a/tests/Validator/NoUnusedVariablesTest.php
+++ b/tests/Validator/NoUnusedVariablesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\NoUnusedVariables;
 
diff --git a/tests/Validator/OverlappingFieldsCanBeMergedTest.php b/tests/Validator/OverlappingFieldsCanBeMergedTest.php
index 6cfc9ed..48d3053 100644
--- a/tests/Validator/OverlappingFieldsCanBeMergedTest.php
+++ b/tests/Validator/OverlappingFieldsCanBeMergedTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\Source;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Schema;
diff --git a/tests/Validator/PossibleFragmentSpreadsTest.php b/tests/Validator/PossibleFragmentSpreadsTest.php
index 5e35cc5..7b51960 100644
--- a/tests/Validator/PossibleFragmentSpreadsTest.php
+++ b/tests/Validator/PossibleFragmentSpreadsTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\PossibleFragmentSpreads;
 
diff --git a/tests/Validator/ProvidedNonNullArgumentsTest.php b/tests/Validator/ProvidedNonNullArgumentsTest.php
index dd5210d..020aefb 100644
--- a/tests/Validator/ProvidedNonNullArgumentsTest.php
+++ b/tests/Validator/ProvidedNonNullArgumentsTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\ProvidedNonNullArguments;
 
diff --git a/tests/Validator/ScalarLeafsTest.php b/tests/Validator/ScalarLeafsTest.php
index 1ec748b..d6ea901 100644
--- a/tests/Validator/ScalarLeafsTest.php
+++ b/tests/Validator/ScalarLeafsTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\ScalarLeafs;
 
diff --git a/tests/Validator/TestCase.php b/tests/Validator/TestCase.php
index b726d72..f8d2efc 100644
--- a/tests/Validator/TestCase.php
+++ b/tests/Validator/TestCase.php
@@ -316,7 +316,7 @@ abstract class TestCase extends \PHPUnit_Framework_TestCase
         $errors = DocumentValidator::validate($schema, Parser::parse($queryString), $rules);
 
         $this->assertNotEmpty($errors, 'GraphQL should not validate');
-        $this->assertEquals($expectedErrors, array_map(['GraphQL\Error', 'formatError'], $errors));
+        $this->assertEquals($expectedErrors, array_map(['GraphQL\Error\Error', 'formatError'], $errors));
 
         return $errors;
     }
diff --git a/tests/Validator/UniqueArgumentNamesTest.php b/tests/Validator/UniqueArgumentNamesTest.php
index 75fc607..bf13064 100644
--- a/tests/Validator/UniqueArgumentNamesTest.php
+++ b/tests/Validator/UniqueArgumentNamesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\UniqueArgumentNames;
 
diff --git a/tests/Validator/UniqueFragmentNamesTest.php b/tests/Validator/UniqueFragmentNamesTest.php
index f465b12..ebc44c7 100644
--- a/tests/Validator/UniqueFragmentNamesTest.php
+++ b/tests/Validator/UniqueFragmentNamesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\UniqueFragmentNames;
 
diff --git a/tests/Validator/UniqueInputFieldNamesTest.php b/tests/Validator/UniqueInputFieldNamesTest.php
index fad836d..031dd0f 100644
--- a/tests/Validator/UniqueInputFieldNamesTest.php
+++ b/tests/Validator/UniqueInputFieldNamesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\UniqueInputFieldNames;
 
diff --git a/tests/Validator/UniqueOperationNamesTest.php b/tests/Validator/UniqueOperationNamesTest.php
index a1f18ef..67b9d39 100644
--- a/tests/Validator/UniqueOperationNamesTest.php
+++ b/tests/Validator/UniqueOperationNamesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\UniqueOperationNames;
 
diff --git a/tests/Validator/UniqueVariableNamesTest.php b/tests/Validator/UniqueVariableNamesTest.php
index 3a003f1..8c86817 100644
--- a/tests/Validator/UniqueVariableNamesTest.php
+++ b/tests/Validator/UniqueVariableNamesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\UniqueVariableNames;
 
diff --git a/tests/Validator/VariablesAreInputTypesTest.php b/tests/Validator/VariablesAreInputTypesTest.php
index 407e5b4..e453fda 100644
--- a/tests/Validator/VariablesAreInputTypesTest.php
+++ b/tests/Validator/VariablesAreInputTypesTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Rules\VariablesAreInputTypes;
 
diff --git a/tests/Validator/VariablesInAllowedPositionTest.php b/tests/Validator/VariablesInAllowedPositionTest.php
index 25dbbd1..9dfe20c 100644
--- a/tests/Validator/VariablesInAllowedPositionTest.php
+++ b/tests/Validator/VariablesInAllowedPositionTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Validator;
 
-use GraphQL\FormattedError;
+use GraphQL\Error\FormattedError;
 use GraphQL\Language\SourceLocation;
 use GraphQL\Validator\Messages;
 use GraphQL\Validator\Rules\VariablesInAllowedPosition;