Fatal error: Uncaught Error: Interface "Symfony\Component\Serializer\SerializerInterface" not found in /srv/disk3/2724534/www/transdoetaskforce.org/concrete/vendor/symfony/serializer/Serializer.php:49 Stack trace: #0 {main} thrown in /srv/disk3/2724534/www/transdoetaskforce.org/concrete/vendor/symfony/serializer/Serializer.php on line 49