diff --git a/src/Executor/Executor.php b/src/Executor/Executor.php
index f06aa73..998038d 100644
--- a/src/Executor/Executor.php
+++ b/src/Executor/Executor.php
@@ -945,7 +945,9 @@ class Executor
                 $hint = "Make sure that type loader returns the same instance as defined in {$info->parentType}.{$info->fieldName}";
             }
             throw new InvariantViolation(
-                "Schema must contain unique named types but contains multiple types named \"$returnType\". $hint"
+                "Schema must contain unique named types but contains multiple types named \"$returnType\". ".
+                "$hint ".
+                "(see http://webonyx.github.io/graphql-php/type-system/#type-registry)."
             );
         }
 
@@ -1136,7 +1138,8 @@ class Executor
             throw new InvariantViolation(
                 "Schema must contain unique named types but contains multiple types named \"$runtimeType\". ".
                 "Make sure that `resolveType` function of abstract type \"{$returnType}\" returns the same ".
-                "type instance as referenced anywhere else within the schema."
+                "type instance as referenced anywhere else within the schema " .
+                "(see http://webonyx.github.io/graphql-php/type-system/#type-registry)."
             );
         }
 
diff --git a/src/Utils/TypeInfo.php b/src/Utils/TypeInfo.php
index a03ecf7..fa97d1b 100644
--- a/src/Utils/TypeInfo.php
+++ b/src/Utils/TypeInfo.php
@@ -106,7 +106,8 @@ class TypeInfo
         if (!empty($typeMap[$type->name])) {
             Utils::invariant(
                 $typeMap[$type->name] === $type,
-                "Schema must contain unique named types but contains multiple types named \"$type\"."
+                "Schema must contain unique named types but contains multiple types named \"$type\" ".
+                "(see http://webonyx.github.io/graphql-php/type-system/#type-registry)."
             );
             return $typeMap;
         }
diff --git a/tests/Executor/AbstractTest.php b/tests/Executor/AbstractTest.php
index 7ae295f..bca67d3 100644
--- a/tests/Executor/AbstractTest.php
+++ b/tests/Executor/AbstractTest.php
@@ -483,7 +483,8 @@ class AbstractTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals(
             'Schema must contain unique named types but contains multiple types named "Test". '.
             'Make sure that `resolveType` function of abstract type "Node" returns the same type instance '.
-            'as referenced anywhere else within the schema.',
+            'as referenced anywhere else within the schema '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).',
             $result->errors[0]->getMessage()
         );
     }
diff --git a/tests/Executor/ExecutorLazySchemaTest.php b/tests/Executor/ExecutorLazySchemaTest.php
index b7d2181..8fd7772 100644
--- a/tests/Executor/ExecutorLazySchemaTest.php
+++ b/tests/Executor/ExecutorLazySchemaTest.php
@@ -185,7 +185,8 @@ class ExecutorLazySchemaTest extends \PHPUnit_Framework_TestCase
 
         $this->assertEquals(
             'Schema must contain unique named types but contains multiple types named "Test". '.
-            'Make sure that type loader returns the same instance as defined in Query.test',
+            'Make sure that type loader returns the same instance as defined in Query.test '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).',
             $result->errors[0]->getMessage()
         );
         $this->assertInstanceOf(
diff --git a/tests/Type/ValidationTest.php b/tests/Type/ValidationTest.php
index 6c062f3..097f5dc 100644
--- a/tests/Type/ValidationTest.php
+++ b/tests/Type/ValidationTest.php
@@ -359,7 +359,8 @@ class ValidationTest extends \PHPUnit_Framework_TestCase
 
         $this->setExpectedException(
             InvariantViolation::class,
-            'Schema must contain unique named types but contains multiple types named "String".'
+            'Schema must contain unique named types but contains multiple types named "String" '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).'
         );
         new Schema(['query' => $QueryType]);
     }
@@ -389,7 +390,8 @@ class ValidationTest extends \PHPUnit_Framework_TestCase
 
         $this->setExpectedException(
             InvariantViolation::class,
-            'Schema must contain unique named types but contains multiple types named "SameName".'
+            'Schema must contain unique named types but contains multiple types named "SameName" '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).'
         );
 
         new Schema([ 'query' => $QueryType ]);
@@ -427,7 +429,8 @@ class ValidationTest extends \PHPUnit_Framework_TestCase
 
         $this->setExpectedException(
             InvariantViolation::class,
-            'Schema must contain unique named types but contains multiple types named "BadObject".'
+            'Schema must contain unique named types but contains multiple types named "BadObject" '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).'
         );
 
         new Schema([