When the help text requests <protocol>://<username>:<password>@<path> I think it’s generally looking for whatever the storage URL is for that storage type. Although you can see some of the URL in Target URL of the job’s Commandline option, to also get authentication credentials you can Export → As Command-line.
Do we know the file is corrupt? The WinRAR test doesn’t count (I think) unless you can get it to decrypt any Duplicati .zip.aes file, but I doubt it can. Duplicati is not using ZIP-format encryption, but ZIP then encryption. Additionally, I prefer to figure out where the problem is happening, in the hope of keeping it from continuing. Right now all I know (unless you have some emails or logs like I showed) is that Duplicati couldn’t download the file as it expected, and most likely it was truncated. Did that occur during upload, during storage, during download, or some other way? Getting back to normal requires having confidence in networks and storage.
Duplicati.CommandLine.BackendTester.exe is one option to see if things are good now. Maybe it was simply something temporarily wrong, but I don’t want to make things worse if the storage is still having any problem.
There’s also no guarantee whatever went wrong didn’t hurt some other file. You could survey for damage by using The TEST command after reshaping your Export → As Command-line a little, or do that in the web UI. Using a larger number of samples takes longer, but the default of 1 sample seems low given known damage.
Meanwhile I’ll see what I can think of for best recovery assuming your Wasabi is OK now and damage is little. You’ve already used most of the primary tools on the initial report. There are a few other tools, but not many.
You’ve got multiple problems, and some are pretty obscure (e.g. “channel is retired” which I hope is just from something else going wrong first). The synthetic filelist is something an interrupted backup normally makes to show what it had gotten thus far, and that warning (note it wasn’t an error) might not be much to worry about. “Unexpected number of remote volumes marked as deleted” has been seen a few times, but isn’t understood.
Is this the most important system to get back up? What about the others? Are there any on Wasabi still OK? While a quick Google search didn’t spot any widespread problems there, how did your systems fail at once?
Another consideration is whether “back to normal” means backing up current data, or keeping access to old. Sometimes a new backup may be started, and the old moved to another Duplicati to see what can be saved. Sometimes people don’t care about old, or repair efforts make things worse, so it’s easier to just begin fresh. Until I hear more about your needs, I’m trying to proceed cautiously, but that definitely can be more difficult…
If anybody else following this has thoughts about a good way to resolve this, feel free to join in on the efforts.