If you had any backups complete, you can look in Complete log in the logs for their RetryAttempts.
Although your issue seems sudden, perhaps there was a sub-critical problem that had grown worse.
number-of-retries can be raised to counter intermittent issues. About → Show log → Live → Retry is another way to see them in real-time. You can click on some of the error lines to see details on them.
An easier plan for long-term monitoring is log-file=<path> and log-file-log-level=retry or higher, but log reveals private information at higher levels such as verbose, so maybe don’t start that high right now.
This is merely a minimal sanity test that access is possible, and a directory list request does not fail.
Duplicati.CommandLine.BackendTester.exe is a somewhat better test, and doesn’t take all that long.
You would give it target URL going to an empty folder, based on URL from Export As Command-line.
Previously mentioned problem Backup to WeDAV / Nextcloud never completes was network issues exhausting retries, which somehow seems to lead to a missing Temp file, then failure of the backup.
No, but similarly-named program duplicity is.
Ideally, however there are some sanity self-checks before backup, and this failed, so no continue.
Currently, the recommended way (when it works…) to interrupt backup is “Stop after current file”.
Next Beta should handle “Stop now”. I’m not sure it handles process kills but you had little choice.
There is no sure-fire way to clear up “Detected non-empty blocksets with no associated blocks!”,
however because it’s likely a problem with a recent file backup, you could try deleting last backup.
Backups are numbered with 0 being the latest. Numbers and dates are also on Restore selector.
If you decide to try this, enter Commandline screen, change Command to delete, and change the
Commandline arguments box to --version=0. Run that and see if it cleanly deletes that version.
Verify files button can repeat the self-check that failed. Maybe test will pass after the deletion.
The other thing that sometimes works is the Repair button on the Database screen, and if you’re
willing, you can use the Create bug report before that, in case posting it will help see the issue.
Manual repairs to the database are sometimes possible, but it’s involved, so let’s try simpler ones.
Excellent idea. When the usual backup stops working, try different things to see what can still work.