Fatal error: Uncaught Error: Interface "Sabre\Xml\XmlSerializable" not found in /server/www/10.1.1.5/htdocs/vendor/sabre/dav/lib/CalDAV/Xml/Property/AllowedSharingModes.php:28 Stack trace: #0 {main} thrown in /server/www/10.1.1.5/htdocs/vendor/sabre/dav/lib/CalDAV/Xml/Property/AllowedSharingModes.php on line 28