Fatal error: Uncaught Error: Interface 'Facebook\PersistentData\PersistentDataInterface' not found in /usr/local/apache/htdocs/plugin/social/libraries/Facebook/PersistentData/FacebookSessionPersistentDataHandler.php:33 Stack trace: #0 {main} thrown in /usr/local/apache/htdocs/plugin/social/libraries/Facebook/PersistentData/FacebookSessionPersistentDataHandler.php on line 33