Fatal error: Uncaught Error: Class 'Sonata\CoreBundle\Serializer\BaseSerializerHandler' not found in /home/lafaamicps/www/symfony/vendor/sonata-project/classification-bundle/Serializer/ContextSerializerHandler.php:21 Stack trace: #0 {main} thrown in /home/lafaamicps/www/symfony/vendor/sonata-project/classification-bundle/Serializer/ContextSerializerHandler.php on line 21