Fatal error: Uncaught Error: Interface 'Symfony\Component\Serializer\Mapping\ClassDiscriminatorResolverInterface' not found in /home/devmecseminars/public_html/mec/vendor/symfony/serializer/Mapping/ClassDiscriminatorFromClassMetadata.php:19 Stack trace: #0 {main} thrown in /home/devmecseminars/public_html/mec/vendor/symfony/serializer/Mapping/ClassDiscriminatorFromClassMetadata.php on line 19