diff --git a/src/Error/UserError.php b/src/Error/UserError.php
new file mode 100644
index 0000000..ad07ee9
--- /dev/null
+++ b/src/Error/UserError.php
@@ -0,0 +1,14 @@
+<?php
+namespace GraphQL\Error;
+
+/**
+ * Class UserError
+ *
+ * Note:
+ * Error that can be display safely to client...
+ *
+ * @package GraphQL\Error
+ */
+class UserError extends InvariantViolation
+{
+}
diff --git a/src/Type/Definition/FloatType.php b/src/Type/Definition/FloatType.php
index dd908cc..363ce27 100644
--- a/src/Type/Definition/FloatType.php
+++ b/src/Type/Definition/FloatType.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Type\Definition;
 
-use GraphQL\Error\InvariantViolation;
+use GraphQL\Error\UserError;
 use GraphQL\Language\AST\FloatValueNode;
 use GraphQL\Language\AST\IntValueNode;
 use GraphQL\Utils;
@@ -50,14 +50,14 @@ values as specified by
     private function coerceFloat($value)
     {
         if ($value === '') {
-            throw new InvariantViolation(
+            throw new UserError(
                 'Float cannot represent non numeric value: (empty string)'
             );
         }
         if (is_numeric($value) || $value === true || $value === false) {
             return (float)$value;
         }
-        throw new InvariantViolation('Float cannot represent non numeric value: ' . Utils::printSafe($value));
+        throw new UserError(sprintf('Float cannot represent non numeric value: %s', Utils::printSafe($value)));
     }
 
     /**
diff --git a/src/Type/Definition/IntType.php b/src/Type/Definition/IntType.php
index 1ab0d8f..ff0dd49 100644
--- a/src/Type/Definition/IntType.php
+++ b/src/Type/Definition/IntType.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Type\Definition;
 
-use GraphQL\Error\InvariantViolation;
+use GraphQL\Error\UserError;
 use GraphQL\Language\AST\IntValueNode;
 use GraphQL\Language\AST\ValueNode;
 use GraphQL\Utils;
@@ -57,7 +57,7 @@ values. Int can represent values between -(2^31) and 2^31 - 1. ';
     private function coerceInt($value)
     {
         if ($value === '') {
-            throw new InvariantViolation(
+            throw new UserError(
                 'Int cannot represent non 32-bit signed integer value: (empty string)'
             );
         }
@@ -67,8 +67,8 @@ values. Int can represent values between -(2^31) and 2^31 - 1. ';
         if (is_numeric($value) && $value <= self::MAX_INT && $value >= self::MIN_INT) {
             return (int) $value;
         }
-        throw new InvariantViolation(
-            'Int cannot represent non 32-bit signed integer value: ' . Utils::printSafe($value)
+        throw new UserError(
+            sprintf('Int cannot represent non 32-bit signed integer value: %s', Utils::printSafe($value))
         );
     }
 
diff --git a/src/Type/Definition/ObjectType.php b/src/Type/Definition/ObjectType.php
index 4bcd153..7a2fd65 100644
--- a/src/Type/Definition/ObjectType.php
+++ b/src/Type/Definition/ObjectType.php
@@ -1,6 +1,7 @@
 <?php
 namespace GraphQL\Type\Definition;
 use GraphQL\Error\InvariantViolation;
+use GraphQL\Error\UserError;
 use GraphQL\Utils;
 
 
@@ -127,7 +128,7 @@ class ObjectType extends Type implements OutputType, CompositeType
             $this->getFields();
         }
         if (!isset($this->fields[$name])) {
-            throw new InvariantViolation(sprintf("Field '%s' is not defined for type '%s'", $name, $this->name));
+            throw new UserError(sprintf("Field '%s' is not defined for type '%s'", $name, $this->name));
         }
         return $this->fields[$name];
     }
@@ -145,7 +146,7 @@ class ObjectType extends Type implements OutputType, CompositeType
             foreach ($interfaces as $iface) {
                 $iface = Type::resolve($iface);
                 if (!$iface instanceof InterfaceType) {
-                    throw new InvariantViolation("Expecting interface type, got " . Utils::printSafe($iface));
+                    throw new InvariantViolation(sprintf('Expecting interface type, got %s', Utils::printSafe($iface)));
                 }
                 $this->interfaces[] = $iface;
             }
diff --git a/tests/Type/ScalarSerializationTest.php b/tests/Type/ScalarSerializationTest.php
index e0be2fa..b097a10 100644
--- a/tests/Type/ScalarSerializationTest.php
+++ b/tests/Type/ScalarSerializationTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace GraphQL\Tests\Type;
 
-use GraphQL\Error\InvariantViolation;
+use GraphQL\Error\UserError;
 use GraphQL\Type\Definition\Type;
 
 class ScalarSerializationTest extends \PHPUnit_Framework_TestCase
@@ -28,28 +28,28 @@ class ScalarSerializationTest extends \PHPUnit_Framework_TestCase
         try {
             $intType->serialize(9876504321);
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Int cannot represent non 32-bit signed integer value: 9876504321', $e->getMessage());
         }
 
         try {
             $intType->serialize(-9876504321);
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Int cannot represent non 32-bit signed integer value: -9876504321', $e->getMessage());
         }
 
         try {
             $intType->serialize(1e100);
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Int cannot represent non 32-bit signed integer value: 1.0E+100', $e->getMessage());
         }
 
         try {
             $intType->serialize(-1e100);
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Int cannot represent non 32-bit signed integer value: -1.0E+100', $e->getMessage());
         }
 
@@ -58,14 +58,14 @@ class ScalarSerializationTest extends \PHPUnit_Framework_TestCase
         try {
             $intType->serialize('one');
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Int cannot represent non 32-bit signed integer value: one', $e->getMessage());
         }
 
         try {
             $intType->serialize('');
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Int cannot represent non 32-bit signed integer value: (empty string)', $e->getMessage());
         }
 
@@ -92,14 +92,14 @@ class ScalarSerializationTest extends \PHPUnit_Framework_TestCase
         try {
             $floatType->serialize('one');
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Float cannot represent non numeric value: one', $e->getMessage());
         }
 
         try {
             $floatType->serialize('');
             $this->fail('Expected exception was not thrown');
-        } catch (InvariantViolation $e) {
+        } catch (UserError $e) {
             $this->assertEquals('Float cannot represent non numeric value: (empty string)', $e->getMessage());
         }