webdav upload: method not allowed

Hi!

I’m facing a problem with uploading a backup to my Nextcloud server via webdav. Webdav config is verified. Uploading results in an error like this:
[2021-01-08 17:00:06] php_system.ERROR: E_ERROR: array ( 'type' => 1, 'message' => 'Uncaught Sabre\\HTTP\\ClientHttpException: Method Not Allowed in /www/htdocs/servername/test.ceecasts.net/wp-content/plugins/xcloner-backup-and-restore/vendor/sabre/dav/lib/DAV/Client.php:232 Stack trace: #0 /www/htdocs/servername/test.ceecasts.net/wp-content/plugins/xcloner-backup-and-restore/vendor/league/flysystem-webdav/src/WebDAVAdapter.php(288): Sabre\\DAV\\Client->propFind(\'https://nextclo...\', Array, 1) #1 /www/htdocs/servername/test.ceecasts.net/wp-content/plugins/xcloner-backup-and-restore/vendor/league/flysystem/src/Filesystem.php(271): League\\Flysystem\\WebDAV\\WebDAVAdapter->listContents(\'\', false) #2 /www/htdocs/servername/test.ceecasts.net/wp-content/plugins/xcloner-backup-and-restore/vendor/watchfulli/xcloner-core/src/Xcloner_File_System.php(710): League\\Flysystem\\Filesystem->listContents() #3 /www/htdocs/servername/test.ceecasts.net/wp-content/plugins/xcloner-backup-and-restore/vendor/watchfulli/xcloner-core/src/Xcloner_Remote_Storage.php(561): watchfulli\\XClonerCore\\Xcloner_File_System->backup_storage_clean', 'file' => '/www/htdocs/servername/test.ceecasts.net/wp-content/plugins/xcloner-backup-and-restore/vendor/sabre/dav/lib/DAV/Client.php', 'line' => 232, ) [] []

What could this be? Thanks!