Warning message: Duplicati.Library.Common.IO.VssBackupComponents

I’ve got exact same warning messages in 3 servers’ backup reports today, but it seems backups were successful.

Here is the message:

2019-12-04 06:30:00 +03 - [Warning-Duplicati.Library.DynamicLoader.DynamicLoader`1-SoftError]: Failed to load process type Duplicati.Library.Common.IO.VssBackupComponents assembly /usr/lib/duplicati/Duplicati.Library.IO.dll, error message: Could not load type of field 'Duplicati.Library.Common.IO.VssBackupComponents:_vssBackupComponents' (1) due to: Could not load file or assembly 'AlphaVSS.Common, Version=, Culture=neutral, PublicKeyToken=959d3993561034e3' or one of its dependencies.

Duplicati Version: (
OS: Ubuntu 18.04 LTS
Kernel: 4.15.0
Mono Version:
Backend: Backblaze B2

Those messages were only found in backup mail report (LimitedWarnings section). I could not find them in log file (log file level is Retry).

Interesting. I have not changed the log file settings, and have not taken a look in the log file; I see that message in the GUI. I have assumed, though, that the warning would get written in the log too with the appropriate log file setting.

So it seems those warnings are not critical, should I skip them?