Error while running differential backup

Hi,

My Nextcloud instance is version 23.0.0 and the Backup app is version 1.0.3.

I have just installed the Backup app and even before first visiting its settings page, the following error started to appear on the Logging app:
[backup] Error: error while running differential backup - [{"file":"\/var\/www\/nextcloud\/apps\/backup\/lib\/Cron\/Backup.php","line":126,"function":"runDifferentialBackup","class":"OCA\\Backup\\Cron\\Backup","object":{},"type":"->","args":[]},{"file":"\/var\/www\/nextcloud\/apps\/backup\/lib\/Cron\/Backup.php","line":115,"function":"runBackup","class":"OCA\\Backup\\Cron\\Backup","object":{},"type":"->","args":[1640836502]},{"file":"\/var\/www\/nextcloud\/apps\/backup\/lib\/Cron\/Backup.php","line":97,"function":"manage","class":"OCA\\Backup\\Cron\\Backup","object":{},"type":"->","args":[]},{"file":"\/var\/www\/nextcloud\/lib\/private\/BackgroundJob\/Job.php","line":51,"function":"run","class":"OCA\\Backup\\Cron\\Backup","object":{},"type":"->","args":[null]},{"file":"\/var\/www\/nextcloud\/lib\/private\/BackgroundJob\/TimedJob.php","line":58,"function":"execute","class":"OC\\BackgroundJob\\Job","object":{},"type":"->","args":[{},{}]},{"file":"\/var\/www\/nextcloud\/cron.php","line":128,"function":"execute","class":"OC\\BackgroundJob\\TimedJob","object":{},"type":"->","args":[{},{}]}]

The same error keeps appearing every 20 minutes. Interestingly, the first full restoring point is scheduled to happen in 2 days, according to the restoring points history, so no differential backup should be running in the first place.

Thank you for your attention.

Start in apps/backup/lib/Cron/Backup.php around lines 97-126, following manage, runBackup, and runDifferentialBackup, then compare that flow with the restoring-points history described in the issue. Done means the app no longer attempts a differential backup before the first full restoring point and the recurring cron error stops.