Fatal error: Uncaught Error: Interface "Symfony\Component\Serializer\Mapping\Loader\LoaderInterface" not found in D:\Webserver\Apache24\htdocs\testephp\signxml\vendor\symfony\serializer\Mapping\Loader\AttributeLoader.php:34 Stack trace: #0 {main} thrown in D:\Webserver\Apache24\htdocs\testephp\signxml\vendor\symfony\serializer\Mapping\Loader\AttributeLoader.php on line 34