Fatal error: Uncaught Error: Interface 'Symfony\Component\Serializer\Mapping\Loader\LoaderInterface' not found in /home/soh-works/www/3good_old/vendor/symfony/serializer/Mapping/Loader/FileLoader.php:21 Stack trace: #0 {main} thrown in /home/soh-works/www/3good_old/vendor/symfony/serializer/Mapping/Loader/FileLoader.php on line 21