Fatal error: Uncaught Error: Interface "Sabre\Xml\XmlSerializable" not found in /var/www/html/nextcloud/apps/dav/lib/CardDAV/Xml/Groups.php:13 Stack trace: #0 {main} thrown in /var/www/html/nextcloud/apps/dav/lib/CardDAV/Xml/Groups.php on line 13