Fatal error: Uncaught Error: Class 'Sonata\CoreBundle\Serializer\BaseSerializerHandler' not found in /home/lafaamicps/www/symfony/vendor/sonata-project/classification-bundle/Serializer/CollectionSerializerHandler.php:19 Stack trace: #0 {main} thrown in /home/lafaamicps/www/symfony/vendor/sonata-project/classification-bundle/Serializer/CollectionSerializerHandler.php on line 19