Fatal error: Uncaught Error: Class "ilXmlWriter" not found in /var/www/html/ilias/components/ILIAS/LearningSequence/classes/Export/class.ilLearningSequenceXMLWriter.php:21 Stack trace: #0 {main} thrown in /var/www/html/ilias/components/ILIAS/LearningSequence/classes/Export/class.ilLearningSequenceXMLWriter.php on line 21