Problem Description
Virtual machine (VM) backup fails during the snapshot creation phase due to a quiescing error.
Cause:
The error indicates that VMware Tools was unable to successfully quiesce the VM during snapshot creation. This is commonly caused by a conflict or malfunction in the VMware VSS Provider service within the guest operating system.
Traceback
method=createVMSnapshot message="VM snapshot creation failed."
Error="An error occurred while quiescing the virtual machine. See the virtual machine's event log for details."
code: 4296146951
actualErrType: *types.ApplicationQuiesceFault
actualMsg: An error occurred while quiescing the virtual machine. See the virtual machine's event log for details.
Resolution:
To resolve the quiescing issue, follow the steps below to disable the VMware VSS Provider service on the affected VM:
Log in to the guest VM (Windows OS).
Press Win + R, type services.msc, and press Enter.
In the Services window, locate the service named VMware Volume Shadow Copy Service Provider or VMware VSS Provider.
Right-click on the service and select Properties.
Change the Startup type to Disabled.
Click Stop (if the service is running), then click OK.
Wait for the next scheduled backup job or manually trigger a backup to verify if the issue is resolved.
Note:
Disabling the VMware VSS Provider service will prevent VMware Tools from coordinating application-level quiescing inside the guest OS. As a result, the backup will be crash-consistent instead of application-consistent.
Crash-consistent backup: Captures data in the same state as it would be after a sudden power loss. It includes all disk data but may not capture in-flight transactions or pending I/O operations.
Application-consistent backup: Uses Microsoft VSS (Volume Shadow Copy Service) to ensure all applications like SQL Server, Exchange, or Active Directory flush their data to disk before the snapshot, providing a clean and recoverable state.
If the VM hosts critical applications (e.g., databases or mail servers), it is recommended to investigate and fix the underlying VSS issue instead of keeping the service disabled permanently.