Fatal error: Uncaught Error: Class "Symfony\Component\Serializer\Serializer" not found in /srv/disk3/2724534/www/transdoetaskforce.org/concrete/src/Foundation/Serializer/JsonSerializer.php:7 Stack trace: #0 {main} thrown in /srv/disk3/2724534/www/transdoetaskforce.org/concrete/src/Foundation/Serializer/JsonSerializer.php on line 7