Volume Shadow Copy not works?

I got error

v15\Server\sqlite3\db.lock => The process cannot access the file ... because it is being used by another process.

What is your --snapshot-policy setting?

by default - off. Ok I understand.

just thought that VSS enabled by default.

What’s the reason for default of --snapshot-policy to be off? I’d think most users would always want that on.

Probably because duplicati doesn’t run as admin by default which is needed for VSS.


As @SirFritz mentions, Duplicati usually runs in the normal user context and this does not have permissions. It is not set to auto either, because that would create error messages in the event log for each backup run.

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But the official help text says:

Setting this to “auto” makes Duplicati attempt to create a snapshot, and fail silently if that was not allowed or supported.

Doesn’t this contradict what you’re saying?

(the official help text is also reproduced in this version of the work-in-progress manual is inaccurate when it says on page 108)

Either way, I’d like to suggest think to @kees-z to mention the snapshot-policy setting more prominently to alert users to the fact that it is off by default. Perhaps mention it in connection with setting up duplicati as a service (as I suppose that is where duplicati is most likely to receive admin rights, thus making it possible to turn --snapshot-policy = on)

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There are two logs: Duplicati’s and Windows.

The “fail silently” part means that Duplicati will not log a warning, but I cannot suppress the Windows event log warning. It would be nice if it was possible to suppress it, but maybe it would also be a security issue that you can “hide your tracks”.

Ideally, I would like to be able to query Windows and say “does the current user have permissions to create a VSS snapshot?” but I have not figure out how to do this.


Thanks a lot for explaining!

IMO, that should somehow be transparent from the help text. Currently, it looks like “auto” is a trouble free option - and then you get those windows warnings…

How about something line this:

“Setting this to “auto” makes Duplicati attempt to create a snapshot, and fail silently if that was not allowed or supported (note that the OS may still issue warnings).”


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