Fatal error: Uncaught Error: Interface "Zend\Feed\PubSubHubbub\CallbackInterface" not found in /home/vincent/http/concrete5/concrete/vendor/zendframework/zend-feed/src/PubSubHubbub/AbstractCallback.php:16 Stack trace: #0 {main} thrown in /home/vincent/http/concrete5/concrete/vendor/zendframework/zend-feed/src/PubSubHubbub/AbstractCallback.php on line 16