Fatal error: Uncaught Error: Class 'Facebook\Helpers\FacebookSignedRequestFromInputHelper' not found in /usr/local/apache/htdocs/plugin/social/libraries/Facebook/Helpers/FacebookJavaScriptHelper.php:31 Stack trace: #0 {main} thrown in /usr/local/apache/htdocs/plugin/social/libraries/Facebook/Helpers/FacebookJavaScriptHelper.php on line 31