Nextcloud Backup don´t start

Hello,

I’m just trying my hand with the backup. (Nextcloud 23.0.0)

I have included 2 different external storage for testing, once another Nextcloud instance, once a SFTP server.

Have configured this in the backup accordingly. If I then want to manually create a full backup, comes the red message text that it will soon be started. But then nothing happens. In the logs I also find nothing about it. The instance also does not change into the maintenance mode.
For the background task I used cron. The job runs correctly every 5 minutes.

I don’t know where to start troubleshooting.

Last night, i got this error message. Don´t know what to do.

error while running differential backup - [{“file”:"/var/www/html/apps/backup/lib/Cron/Backup.php",“line”:126,“function”:“runDifferentialBackup”,“class”:“OCA\Backup\Cron\Backup”,“object”:{},“type”:"->",“args”:},{“file”:"/var/www/html/apps/backup/lib/Cron/Backup.php",“line”:115,“function”:“runBackup”,“class”:“OCA\Backup\Cron\Backup”,“object”:{},“type”:"->",“args”:[1640977803]},{“file”:"/var/www/html/apps/backup/lib/Cron/Backup.php",“line”:97,“function”:“manage”,“class”:“OCA\Backup\Cron\Backup”,“object”:{},“type”:"->",“args”:},{“file”:"/var/www/html/lib/private/BackgroundJob/Job.php",“line”:51,“function”:“run”,“class”:“OCA\Backup\Cron\Backup”,“object”:{},“type”:"->",“args”:[null]},{“file”:"/var/www/html/lib/private/BackgroundJob/TimedJob.php",“line”:58,“function”:“execute”,“class”:“OC\BackgroundJob\Job”,“object”:{},“type”:"->",“args”:[{},{}]},{“file”:"/var/www/html/cron.php",“line”:128,“function”:“execute”,“class”:“OC\BackgroundJob\TimedJob”,“object”:{},“type”:"->",“args”:[{},{}]}]

I am getting the same error. Does anybody have a clue?