Comment 5 for bug 1247392

After some testing, I think I know what could cause this (now very old) bug. There was a bug in deja-dup/duplicity that allowed for an accidental change in password when making the occasional full backup checkpoint (bug 918489, fixed in deja-dup 34.3).

Here's how this would be reproduced, using deja-dup <= 34.2:
- Create a new backup with password 'a'
- Keep backing up until deja-dup decides to make a new backup. Then either have a different password saved in gnome-keyring or enter a different password when it prompts. Say, 'b'
- Now you have two backup chains with different passwords, but deja-dup will keep adding new backups.
- Until either your cache gets blown away or deja-dup decides to do its every-two-months backup-validation check. (Or heaven forbid, your hard drive gets blown away and you need to restore.)
- When either happens, duplicity will try to download the encrypted manifest files for all the backups and deja-dup will prompt you for the decryption password.
- If you enter 'a', it will choke on your second backup and show the password prompt again. If you enter 'b' it will choke on the first. Thus you get eternal backup prompts.

The only way to recover is to blow away older backups (or the whole thing) and start over. If you were trying to restore, your files can be manually recovered using duplicity though.

Anyway. That's my research into what this bug was likely about. I'll mark it as a dup of bug 918489 (which has been fixed).