Fatal error: Uncaught Error: Interface "Sabre\Xml\XmlSerializable" not found in /usr/home/jiexusheng/domains/linuxdo.isgre.at/public_html/vendor/sabre/dav/lib/CalDAV/Xml/Notification/NotificationInterface.php:17
Stack trace:
#0 {main}
  thrown in /usr/home/jiexusheng/domains/linuxdo.isgre.at/public_html/vendor/sabre/dav/lib/CalDAV/Xml/Notification/NotificationInterface.php on line 17