The installed VSS Providers can be found in the following Registry Key: HKLM\SYSTEM\CurrentControlSet\Services\VSS\Providers\
It is highly advisable to export any key prior to removing it from the registry.
If the above troubleshooting steps does not resolve this issue, please review the solution on the this article http://www.veeam.com/kb1846.
The issue described in this article has been observed when a Hyper-V VM was converted or restored to a VMware environment. Afterward the now VMware VM retained its "Hyper-V IC Software Shadow Copy Provider", the presence of this Provider was determined to be the cause of the VSS_E_UNEXPECTED_PROVIDER_ERROR error. The backup admin was able to remove the Hyper-V IC Software Shadow Copy Provider provider manually and the error no longer occured.
The following is a non-exhaustive list of VSS providers which Veeam customers have reported had to be removed to resolve the issue described in this article:
- Data ONTAP VSS Hardware Provider
- Acronis VSS SW Provider
- Symantec Software VSS Provider
- StorageCraft Volume Snapshot Software Provider
- Backup Exec VSS Provider
- Dell EqualLogic VSS HW Provider
- Nimble Storage VSS Provider
- Azure Site Recovery VSS Provider
- VSS LifeLine HW Provider
- HP MSA 1040/2040 VSS Provider