If there’s any log or anything else (except the backup data / credentials). I’m happy to provide it. If’s suspected it could have something to do with the local Duplicati database, I can zap it and restart that backup set. But generally that should be a bad solution. Backing up works perfect, it’s just verification which fails strangely.
I also experimented with alternate setup, for an environment where I would need to use VSS (WIndows Server) and got AlphaVSS DLL (missing?) error? There are no up to date open issues on GitHub about this… So is it know issue, or nobody’s just using it? Did I just mess up something? - I can dig the complete error from logs, or reproduce it tomorrow, if necessary. I’ve got environments where VSS would be now useful.
I did clean setup with latest canary on the system, and for some reason, I’m not getting AlphaVSS DLL error anymore. So that’s awesome. Don’t know what the issue actually was. But now it’s all good and working. - My bad, now it was reset to auto, which of course “works” but doesn’t work as desired.
On other server I’ll get this error:
Failed to initialize windows snapshot instance => Could not load file or assembly 'C:\Program Files\Duplicati 2\AlphaVSS.x64.dll'. The specified module could not be found.
Fatal error => Failed to create a snapshot: Could not load file or assembly 'C:\Program Files\Duplicati 2\AlphaVSS.x64.dll'. The specified module could not be found.
That error message is (probably) just misleading. It’s most likely related to the user rights / system role / file system settings. Yet it says “could not be found”. I’ve checked file is in the directory and readable by the user. - Messages like that could mislead users and make trouble shooting harder. ( I’ve got similar issues with other platforms and programs every day ).
No error: $null = Get-Content "C:\Program Files\Duplicati 2\AlphaVSS.x64.dll"
Based on some analysis, I think it should work without changes. But probably I need to replace some files. Just wondering if correct files are shipped with setup?
System.IO.FileNotFoundException: Could not load file or assembly 'C:\Program Files\Duplicati 2\AlphaVSS.x64.dll'. The specified module could not be found.
File name: 'C:\Program Files\Duplicati 2\AlphaVSS.x64.dll'
at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
at Alphaleonis.Win32.Vss.VssFactoryProvider.DefaultVssAssemblyResolver.LoadAssembly(AssemblyName assemblyName)
at Alphaleonis.Win32.Vss.VssFactoryProvider.LoadAssembly()
at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
at System.Lazy`1.CreateValue()
at Alphaleonis.Win32.Vss.VssFactoryProvider.GetVssFactory()
at Duplicati.Library.Snapshots.Windows.AlphaVssBackup.CreateVssBackupComponents()
at Duplicati.Library.Snapshots.Windows.AlphaVssBackup.GetVssBackupComponents()
at Duplicati.Library.Snapshots.Windows.AlphaVssBackup.Create()
at Duplicati.Library.Snapshots.Windows.SnapshotManager..ctor(SnapshotProvider provider)
at Duplicati.Library.Snapshots.WindowsSnapshot..ctor(IEnumerable`1 sources, IDictionary`2 options, Boolean followSymlinks)
2025-04-16 10:17:01 +03 - [Information-Duplicati.Library.Main.Operation.BackupHandler-SnapshotFailed]: Failed to create a snapshot: Could not load file or assembly 'C:\Program Files\Duplicati 2\AlphaVSS.x64.dll'. The specified module could not be found.
Ref:
This seems to be the best tread about the problem, if I can’t resolve it trivially. I’ll continue here:
In all cases it started to work by replacing files. I’ll try the same.
Continued here: Missing AlphaVSS.x64.dll error on clean install - #23 by Sami_Lehtinen