Fatal error: Uncaught Error: Class "Symfony\Component\Serializer\Mapping\Loader\FileLoader" not found in /media/jean/learning/huagai/drupal/vendor/symfony/serializer/Mapping/Loader/YamlFileLoader.php:28 Stack trace: #0 {main} thrown in /media/jean/learning/huagai/drupal/vendor/symfony/serializer/Mapping/Loader/YamlFileLoader.php on line 28