Fatal error: Uncaught Error: Class "Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer" not found in D:\Webserver\Apache24\htdocs\testephp\signxml\vendor\symfony\serializer\Normalizer\ObjectNormalizer.php:32 Stack trace: #0 {main} thrown in D:\Webserver\Apache24\htdocs\testephp\signxml\vendor\symfony\serializer\Normalizer\ObjectNormalizer.php on line 32