The issue was firstly caught by TSM. The backup job of a virtual machine failed and the log shows 02/22/2014 04:09:37 ANS4015E Error processing ‘virtual-machine-name‘: unexpected TSM error (115) encountered.
My understanding is that the first step of TSM backup is to take a snapshot. So I tried to manually take a snapshot of the running virtual machine (Win 2012) to see how it goes. Then I enabled ‘quiescing the file system’ and clicked to take a snapshot, it failed either. Now I confirm it is not a TSM issue but a VSS issue.
Login into the Windows 2012, I found there is a VSS error – “Volume Shadow Copy Service error: Unexpected error calling routine RegQueryValueExW({564d7761-7265-2056-5353-2050726f7669},,…). hr = 0x80070002, The system cannot find the file specified.” It seems the VSS was calling for a invalid provider ID, to confirm it I ran “vssadmin list providers” to double check.
Yes, the {564d7761-7265-2056-5353-2050726f7669} is not listed as a valid provider ID. But what hell is it? It looks like a virtual machine UUID. Not sure exactly where it came from. But it definitely has something to do with an outage we had last week, the TSM was taking snapshot of this virtual machine then suddenly a network outage stopped the creation process. This may lead to some weird thing left in the virtual machine I guess.
After removed the provider ID from the registry, I was able to take a snapshot. So did the TSM backup.
Jackie Chen's IT Workshop 
Hi,
What did you do to find th VSS error? I have the same error below :
“ANS4015E Error processing ‘virtual-machine-name‘: unexpected TSM error (115) encountered.”
Thanks
check the windows event log
I was having these odd errors too suddenly and tried all of VMWare’s suggestions to no avail….
Thank you, Jackie!!!
Saved Me from crazyness. !!
Spot on that man!
cheers
Mark
Thank you. This solution resolved VM backup issue for me.
I’ve been searching for a reason why backups haven’t been happening and this was precisely the reason why. Thank you for posting this article that was very searchable via Google.
5 years later, and still a better fix than anything Veeam can suggest 🙂
7 years later and solved my issue!