Anyway, this is what I did to get rid of the 68 errors.
- Go to the log and list the files with the cryptographic errors (it only lists 20 at a time)
- Go to the fileset and delete each one, using search. The first 5 characters (not counting “Duplicati-” should be enough to find that specific file
- When you delete all 20 (or whatever’s left), do database//repair (should only take 1 second)
- Do ANOTHER backup. This time, it should go quite a bit faster, as Duplicati doesn’t have to retry each file 5 times during “verify files” phase
- Your errors should decrease by 20. (68 → 48)
- Repeat the process until all errors are eliminated (68 → 48 → 28 → 8 → 0)
Instead of taking 1 hour 15 min, backup now takes less than 15 minutes.