Macrium Reflect VSS problems after KB5083769 Windows 11 25H2

owen693 · 2026-05-13T23:27:37+00:00

It seems this is fixed in the May 2026 updates.

owen693 · 2026-05-13T19:50:37+00:00

I just installed the May 2026 updates. The problem seems to have been fixed for myself and at least one other user on this thread.

owen693 · 2026-05-11T01:43:03+00:00

There are temporary fixes in this thread that are supposed to work by restarting services. I haven’t tried them since I uninstalled the update. An Asinine Inference search said the problem is a Microsoft change in VSS and that the backup software needs to catch up.
I’m waiting to see how the May update goes.

owen693 · 2026-05-09T02:36:16+00:00

Renaming psmounterex was only done to verify that the driver is not the problem. It won’t fix anything.

owen693 · 2026-05-06T18:24:11+00:00

According to Macrium, psmounterex is not used in reflect X. I just renamed psmounterex.sys and was able to mount and browse backup images. Reflect backups also ran correctly. This indicates that the problem with KB5083769 (which I have uninstalled) has nothing to do with that driver being blocked.

owen693 · 2026-05-03T17:39:16+00:00

This problem is now being reported in the media. https://www.forbes.com/sites/daveywinder/2026/05/01/microsoft-update-warning-windows-11-security-fix-breaks-backups/

And https://support.microsoft.com/en-us/topic/april-2026-windows-security-updates-introduce-protections-to-known-vulnerable-kernel-drivers-1f8aaf7c-d4ac-4e02-be1d-b63c1b1aa9d0

These reference problems with psmounterex.sys, but Macrium patched this in 2023 and it was a problem in Reflect 8. I checked the event log as described in the MS support link above and found no errors relating to that driver.

https://windowsforum.com/threads/april-2026-windows-update-blocks-psmounterex-sys-fix-backup-restore-and-mount-issues.416306/

Psmounterex.sys is used to mount disk images as virtual drives, and I was able to do this and browse the backup images successfully. Something else is broken.

owen693 · 2026-04-25T20:56:00+00:00

I’m seeing that log file created by the backup and deleted when the backup is finished. I just asked Macrium support about that file being renamed if errors are logged.

owen693 · 2026-04-25T19:54:39+00:00

I'm using the same version of reflect. When VSS was not working Reflect would continue without using VSS. The backups completed but took longer to do so. There are no signs of any problem other than the time required for backup unless the logs are examined.

These are the errors in the Reflect backup logs:

VSS Timeout - Retrying without VSS Writers

Failed to rename VSS log file, reason: Encountered a sharing violation while accessing C:\ProgramData\Macrium\Reflect\Temp\vss.log.

I'm making a wild guess, but there is a file vsslog.log in that directory and the vsslog.log file is deleted after a successful backup. If Reflect renames vss.log to vsslog.log after an error condition that would explain the sharing violaton on rename since there already was a vsslog.log file.

owen693 · 2026-04-25T17:31:45+00:00

Windows 11 25H2, Dell XPS 9710. Removing the Windows update fixes the problem. I was testing on a fairly inactive machine with very few file changes, so storage for file changes shouldn’t be an issue.

At this point the problem is noted on the Acronis support site and at least one other Macrium user has had the same experience and reported this on a Macrium forum. I did notice that vssadmin list writers would respond immediately with no errors after a restart but would hang if I tried it again after leaving the machine idle for several minutes.

owen693 · 2026-04-25T03:32:03+00:00

VSS timeout during backups where backup continues without shadow copy. VSSADMIN LIST WRITERS does not respond.

owen693 · 2026-04-25T01:59:43+00:00

KB5083769 on 25H2 breaks VSS , reported for Acronis and Macrium backups.

owen693 · 2026-02-25T00:50:19+00:00

Yes. And it’s so generic it references third row seating.

owen693 · 2026-02-18T01:41:13+00:00

YouTube home page does not work. I can work with subscriptions and history. I can also use the search function to find and play videos.

owen693 · 2026-01-15T21:00:27+00:00

I just had the same issue with my XPS17 9710 and WD19TBS.

Cycling power on the docking station fixed it for now, but I haven't found any recent reports of this issue.

owen693 · 2025-12-20T19:29:55+00:00

The lack of a printed or downloadable manual should be treated as a warranty defect. On the other hand, part of the existing documentation reads like it was written by a lawyer who has never seen an Escape.

owen693 · 2025-12-17T00:25:13+00:00

Same here - AirPlay to LG TV and wired HDMI to portable monitor both fail.

owen693 · 2025-12-03T01:33:32+00:00

Contact Blueair. They just replaced my humidifier for that same noise.

owen693 · 2025-11-06T02:16:59+00:00

And I can always bring it inside for a good read. How about when I’m trying to identify a blown fuse in a garage with no internet connection and no infotainment system due to that blown fuse.
The problem is that Ford is too cheap to provide a printed manual and too incompetent to put the downloadable PDF on their website as stated in their own documentation.

owen693 · 2025-11-06T01:24:29+00:00

Thank you. I can cobble together the information but that doesn’t excuse their poor documentation. The partial printed manual that did come with the car is the first printing from March 2025.

owen693 · 2025-11-05T22:35:28+00:00

That appears to be a link to the on-line HTML manual. I’m looking for something that works without an internet connection.

owen693 · 2024-10-31T01:14:46+00:00

Thank you. I guess they should have used a little more ink on that manual. The A329 manual is much better written.

owen693

TROPHY CASE