Comment 6 for bug 1651396

Thanks for this log. It shows that your current backup chain started on Oct 10, contains the offending incremental backup (Dec 19 to Dec 20), and has later incremental backups (three more on Dec 20, one on Dec 21, one on Dec 22, one on Dec 30). You can see for yourself under "primary backup chain" (you also have 9 older backup chains).

So your backups are apparently still performed, despite the error message (!?!).

As far as I understand, the SHA1 hash mismatch means that the indicated file (first volume of Dec 19 to Dec 20 incremental backup) is different from when it was created and its SHA1 hash was written in the accompanying .manifest file (a text file that stores the hashes of each volume at creation time). Is it conceivable that the transfer of this file to your backup location failed somehow? Or that it was modified afterwards?

I think the easiest way for you to get rid of this issue is to delete (or rather, move away) the tail of your current backup chain, starting at the offending file, and launch an incremental backup to cover the Dec 19 to today period.

That won't tell us how this file got corrupted however, but I for one am not able to help further.

You may also want to delete (or rather move away) Déjà-Dup's cache directory (~/.cache/deja-dup) in case something weird creeped into it and is causing a problem. It will be recreated with fresh information downloaded from the backup location (manifest and signature files).