Backup job fails - claiming that path could not be found

starting last Tuesday, one of my backup jobs failed to run with the terse message “at least one error occurred” - and no hint where to find details on the error (different topic).
Luckily I had set up a lof file where I found the message where it bailed out:

2022-10-15 16:19:50 +02 - [Retry-Duplicati.Library.Main.Operation.Backup.BackendUploader-RetryPut]: Operation Put with file attempt
1 of 6 failed with message: Ein Teil des Pfades “\?\X:\L520 Win10\Duplicati\D\” konnte nicht gefunden werden.

meaning : “a part of the path … could not be found”.

In a way this is true, because I can’t find a file with the name at the specified location.
FWIW When I try multiple time times the filename in the error message changes.
The location \?\X:\L520 Win10\Duplicati\D\ definitely does exist. I configured a clone of the same job, just changed the destination path to \?\X:\L520 Win10\Duplicati\DD\ - and it worked OK. So there’s nothing wrong with the path as such.
But why does the original job fail all of a sudden?
Is there a way to fix this hiccup?
It wouldn’t be much of a loss to dump the old backup and set up a new one. However if possible, I’d prefer to fix it and thus maintain the history in duplicati-monitoring, where I reported all previous runs.
And of course I’d prefer to understand what went wrong and learn how to fix it :slight_smile:

The forum is turning double backslash into single. Use backticks to avoid that. If I follow, you moved to
\\?\X:\L520 Win10\Duplicati\DD\ instead of single D folder, and that works, whereas D does not?
Weird. Are these folders on a local drive or something remote that might be going away occasionally?

The “part of the path” probably means the drive or an initial folder. Without a folder, can’t write the file.
I think (haven’t tested) you should be able to do something like a Command Prompt dir of the folder.
Make sure you’re doing it as the same user the Duplicati runs as. Does it work when Duplicati won’t?

We don’t know whose hiccup it is. Did you troubleshoot any more by restarting Duplicati or Windows?
If the problem is still around, you could run the Command Prompt test or even look in Process Monitor.
The output is hard to read (I think this is an internal Windows view), but indicates requests and results.

Here’s how a DirectoryNotFoundException is induced in PowerShell which is written in C# like Duplicati.
You can try a similar test to see if you can get the C# error (based on a Windows error) more like yours:

PS C:\> echo test > C:\missingfolder\test.txt
out-file : Could not find a part of the path 'C:\missingfolder\test.txt'.
At line:1 char:1
+ echo test > C:\missingfolder\test.txt
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OpenError: (:) [Out-File], DirectoryNotFoundException
    + FullyQualifiedErrorId : FileOpenFailure,Microsoft.PowerShell.Commands.OutFileCommand

PS C:\>

Sorry, I wasn’t aware of the forum quirk with backslashes.


That’s also what I think :-\

The path is on a local NAS, in the local (W)LAN and I can access the path through my Windows share, as I used to do before. That’s why I set up this other job with just a minimal modification to the path for a test.

Thanks for the hint with Procmon. It confirmed a FAIL for path in question.

And even weirder: After some testing (where the DD job also failed) the sky turned blue again and all jobs suddenly again ran like a charm :astonished:

So I’m glad it works, but some sneaky feeling remains about the reason …

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