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Hi there,

Veeam B&R 12 is installed on a Windows 2022 Server, which is installed on VMWare ESXi 6.5 U3. From there I backup our produtvie Server, which is a VMWare ESXi 6.7 with a Windows Server 2016 and a Windows Server 2012 R2 (Exchange Server) installed on it. Everything works fine, exept the backup of the Windows 2012 R2 Server. It does backup, but I receive the Warning “Failed to index guest file system. VSS Control: Index failed". Is there any way to fix this, except disabling the file indexing?

Hello @Michail 

There is not enough disk space in the guest OS to run the agent and start VSS. You need to free up disk space on the system of the VM you are trying to back up. Try to free up at least 1GB of space. After this, run the job again.


Thankes a lot Moustafa for your advice. I checked free space and it was lower than i thought. but still there were 41 GB of 200 GB free. So that should have done it. Anyway, I cleaned up the System and got additional 10 GB now. I will report wether this has any impact or effect.


Hi @Michail , looking forward to your feedback and I hope your problem to be solved.


If keeping file indexing enabled is extremely important, please open a support case with log files attached.

That being said, why is file indexing enabled on your Exchange server? You don’t need it for any kind of restores using the Veeam Explorer for Exchange. Even if you store a lot of files on the Exchange server, you can still restore them without indexing using the Backup Browser.

My recommendation here would honestly be to simply disable file indexing.


Maybe there’s a VSS writer in failed state?


If we are making guesses on why it fails, I think a more likely reason is that it times out because the threshold on Exchange servers is smaller than otherwise. Why why does it timeout? Most likely because the server is just too busy, which again could be a resources constraint - maybe monitor storage read latency during the backups.


Well, I tried all of your advices and it worked 🙂 I cleaned up Exchange Server and won 10 GB extra space on disk and I started VSS Service (which was stopped); now backup is free from warnings. Thankes a lot again guys :)


Well, I tried all of your advices and it worked 🙂 I cleaned up Exchange Server and won 10 GB extra space on disk and I started VSS Service (which was stopped); now backup is free from warnings. Thankes a lot again guys :)

Perfect. 👍


I have a different error- Failed to index guest file system. Failed to zip folder 'c:\users\.....Appdata\Local\Temp\GuestIndexData.zip. 

I am seeing the below warning on backup jobs. We have VEM installed so cannot disable Guest indexing. Backup will complete successfully with this warnings. Using Domain admin account for Guest processing and indexing. Please help.

Warning :Failed to index guest file system. Failed to zip folder 'C:\Users\tn\AppData\Local\Temp\66ddcb73-b3b1-4fea-8333-ffa67ef9aace' to file 'C:\Users\tn\AppData\Local\Temp\66ddcb73-b3b1-4fea-8333-ffa67ef9aace\GuestIndexData.zip'VBRCatalog is saved in C: drive and have 386 GB free of 599 GB

VBR 12.1 version VEM 12.1

r/Veeam - Failed to index guest file system. Failed to zip folder 'c:\users\.....Appdata\Local\Temp\GuestIndexData.zip


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