Fatal error: Uncaught Error: Interface "Doctrine\Common\Collections\Collection" not found in /var/www/apache/dev/cal/web/vendor/doctrine/orm/lib/Doctrine/ORM/PersistentCollection.php:47 Stack trace: #0 {main} thrown in /var/www/apache/dev/cal/web/vendor/doctrine/orm/lib/Doctrine/ORM/PersistentCollection.php on line 47