Virtual Server failing to backup since December - Troubleshooted extensively

Question

Virtual Server failing to backup since December - Troubleshooted extensively

Nick Tello 20

Starting in Dec of 2025, a virtual server of ours has been failing its nightly backup.

The "Backup Pre-Check" reports Snapshot operation failed due to COM+ error with a sudgested action of Please restart windows service "COM+ System Application" (COMSysApp). If the issue persists,, restart the VM. We have done so with no resolution.

Latest backup attempt failure information below.

Error Code

ExtensionSnapshotFailedCOM

Error message

Snapshot operation failed due to COM+ error

Recommended action

Please restart windows service "COM+ System Application" (COMSysApp). If the issue persists,, restart the VM.

VM was last rebooted a few days ago despite issue starting in December.

Have tried removing from recovery vault and keeping backup data (for HIPA compliance reasons), and then readding but no success.

Need assistance determining why this is failing and how to get it back to a healthy backup state without losing historical data. If fix will require a reboot or any interruption to the servers use, it will need to occur after hours due to this server supporting medical treatment.

Nick Tello 20 Reputation points

2026-04-17T12:52:08.1166667+00:00

Thanks for your posts. I was pulled away for another issue, and am revisiting this now. So i did investigate the VSS writers and Com+. The VSSADMIN looks health at first as seen in the screenshot

However I did find error logs for VSS in the application event logs occurring at pretty much every backup time. 2 errors occurred back to back twice each time the backup runs. I've included both.

The backups run for about 7-7.5 hours before they fail with these errors. This is pointing me towards the VSS install being corrupt being our root cause. What is the best way to go about addressing this issue though? Will we need a maintenance window for the customer, or can this be done in a non-disruptive manner?
My next planned troubleshooting step was to delete and recreate the iaasvmprovider but now I'm inclined to believe its the VSS.

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Nick Tello 20 Reputation points

2026-04-17T12:52:08.1166667+00:00

Thanks for your posts. I was pulled away for another issue, and am revisiting this now. So i did investigate the VSS writers and Com+. The VSSADMIN looks health at first as seen in the screenshot

However I did find error logs for VSS in the application event logs occurring at pretty much every backup time. 2 errors occurred back to back twice each time the backup runs. I've included both.

The backups run for about 7-7.5 hours before they fail with these errors. This is pointing me towards the VSS install being corrupt being our root cause. What is the best way to go about addressing this issue though? Will we need a maintenance window for the customer, or can this be done in a non-disruptive manner?
My next planned troubleshooting step was to delete and recreate the iaasvmprovider but now I'm inclined to believe its the VSS.

Answer 1

Hi Nick Tello ,

The error you’re seeing (ExtensionSnapshotFailedCOM) usually points to something deeper than just the COM + service itself. Restarting COMSysApp or the VM is the first line of defense, but since you’ve already tried that, we’ll need to dig a bit further. In many cases, this comes down to either corrupted COM + catalog components or conflicts with the VSS (Volume Shadow Copy Service) writers that the backup relies on. I’d suggest checking the Application Event Logs around the time of the backup failure to see if any VSS writer errors are logged, that often gives a clue which component is misbehaving.

Another angle: make sure the VM’s OS is fully patched, since there have been fixes rolled out for COM + and VSS stability in recent updates. If you’re running any third-party antivirus or endpoint protection, temporarily disabling it during backup (after hours, of course) can help rule out interference. If none of that clears it up, the next step would be to re-register the COM + catalog and VSS writers, that’s a bit more invasive, so I’d recommend scheduling it after hours given the medical workload this server supports. Importantly, none of these steps should cause you to lose historical backup data in the vault.

If this guidance proves helpful, feel free to click “Accept Answer” so we know we’re heading in the right direction and let me know if you need any assistance. Thank you!

HLBui 12,140 Reputation points Independent Advisor

2026-04-17T09:38:01.4666667+00:00

Just checking to see how is everything. Please feel free to let me know if you need any assistance
Nick Tello 20 Reputation points

2026-04-29T17:47:54.5333333+00:00

The VSS writers ended up being the problem. This issue has been resolved. Thread may be closed. Thank you for your assistance!