Fatal error: Uncaught Error: Class "ilXmlWriter" not found in /var/www/html/ilias/components/ILIAS/Chatroom/classes/class.ilChatroomXMLWriter.php:24 Stack trace: #0 {main} thrown in /var/www/html/ilias/components/ILIAS/Chatroom/classes/class.ilChatroomXMLWriter.php on line 24