Fatal error: Uncaught Error: Interface "Sabre\Xml\XmlSerializable" not found in /var/www/cal.digio.space/vendor/sabre/dav/lib/CalDAV/Xml/Notification/NotificationInterface.php:17 Stack trace: #0 {main} thrown in /var/www/cal.digio.space/vendor/sabre/dav/lib/CalDAV/Xml/Notification/NotificationInterface.php on line 17