Solved Macrium Reflect 8 -VSS Timeout

Just experienced this VSS failure on 2 PC's, one running MR8 Free and the other a licensed version of MR8. The log shows:

MR takes 5-10 minutes to complete the retrying process and seems to eventually succeed. After this Windows Explorer did not open correctly on one PC (maybe unrelated).

A search for this problem turned up a Reddit post that this was experienced on Windows 11 25H2 after the install of KB5083769, and it also affected Acronis. They uninstalled that KB but I have not tried that. Will wait and see if MS makes a change.

Have you tried "Fix VSS problems..." from the "Other Tasks" menu in MR (any version)?

Yes, that did not help. MR actually spenf 15 minutes trying to create a Volume Shadow Copy, produced that failure message, then proceeded normally.

A user in the in the MR forum reported the support just says that it is a Windows problem. The Acronis Support Portal provides a bit more detail, but no immediate suggestions other than to uninstall KB5083769.

Have you checked to see if VSS is starting on computer boot up?

I'm not seeing this issue. I just successfully created and verified three backups on three computers.
A Gen 8 and Gen 11, both on 8.0 Free and a Gen 14 on 8.1 paid. All are i7's.
All are on KB5083769, 26200.8246.

MR 8.1.8853 runs fine here with KB5083769, though there are various reports of other issues, including
(which problem Brink mentions in the News article on the update)
and MS says


Just wondering- does System Restore still run if you're experiencing VSS issues?

The problem seems be resolved after running the script below. It was developed after some detective work with MS Copilot. The analysis of the problem is:

Running the command "vssadmin list writers" should produce a list of about 7 writers, but the process hangs and does not produce anything. This indicates that the COM+ catalog was in a partially corrupted state after the install of KB5083769. Two of my PC's experienced this problem, but not on a third one. Re-registering the servers and rebooting temporarily resolved the issue allowing the vssadmin to run normally, but then running Macrium Reflect 8 triggering the broken COM registrations.

The corruption was subtle enough that Windows didn’t auto‑repair it. A rebuild forced Windows to regenerate the modern COM+ catalog from CBS.

This is the fix script that was run from an elevated command prompt:

cd C:\windows\system32

dism /online /cleanup-image /restorehealth
sfc /scannow

regsvr32 /s vss_ps.dll
regsvr32 /s eventcls.dll
regsvr32 /s es.dll
regsvr32 /s swprv.dll
regsvr32 /s vssui.dll
regsvr32 /s msxml3.dll
regsvr32 /s msxml6.dll

net stop vss
net stop swprv
net stop eventsystem
net stop COMSysApp

net start COMSysApp
net start eventsystem
net start swprv
net start vss

Then reboot.

So far it seems to be working as successive runs of MR8 are fine.

NOTE: The above is only a temporary fix for a small number of PC's that are affected. The problem will return, maybe within 10 minutes.

Absolutely stunning fix. In awe. Thank you so very much

AskWoody's "Patch Lady" (Susan Bradley) reported on this today if this helps anyone:

On the same day I sent out an MS-DEFCON Alert recommending installing the April updates, Ira Shapiro alerts us to issues with backup software. I’m not seeing this with all backup software, but some vendors have mentioned the matter in various forums.
The problem with KB5083769 (the Windows 11 24H2 and 25H2 April update) is serious enough that I’m raising the MS-DEFCON level to 3.
As usual, don’t panic. The problem does not affect all backup software. Check your system first before following my recommendation below, and consult your vendor’s site for its updates.
Here’s a sampling of posts from some of the vendors.

• Urbackup is having issues and recommends uninstalling KB5083769 if you are impacted.
• Macrium is reporting issues with Reflect in a Reddit thread.
• Acronis posted a support note indicating that it is investigating. However, the note also recommends uninstalling KB5083769 and rebooting.

If you are impacted:

• Go to Settings | Windows Update | Update history.
• Scroll down to the end and find the section Related settings.
• Click on Uninstall updates.
• Look for Security update for Microsoft Windows (KB5083769).
• Click the uninstall link on the right.
• Return to Windows Update.
• Pause updates.

The error appears to be with the Microsoft Volume Shadow Copy Service (VSS). This vital Windows component is used with many backup and restore solutions. However:

• It is not used with the Windows 11 cloud-based Backup feature.
• It is used with the forthcoming point-in-time restore (PITR) feature in Windows 11 (KB5070307).

Some of us can't uninstall KB5070307. Here is some information I got from Macrium support. There is a workaround, and they are working on a permanent fix.

---

The issue you are experiencing is related to a recent Windows update that has expanded Microsoft’s vulnerable driver blocklist. As a result, the psmounterex.sys driver used by Macrium Reflect for image browsing is being blocked from loading by Windows security features.

This driver is responsible for mounting backup images so they can be accessed via the “Browse” function. When it is blocked, backups themselves are unaffected, but you will not be able to mount or explore them within Windows.

As a workaround, you can temporarily disable the vulnerable driver blocklist by doing the following:

1. Open Registry Editor

2. Navigate to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CI\Config

3. Set the value of:
VulnerableDriverBlocklistEnable to 0

4.Restart the system

Alternatively, this setting may also be controlled through Windows Security / Device Security / Core Isolation / Memory Integrity.

Please note that disabling this feature reduces system security, as it allows drivers that Windows has flagged as vulnerable to load. Because of this, it is recommended only as a temporary workaround.

Using Macrium Reflect for backup and restore operations will continue to function normally, as this issue only affects the image mounting feature.

---

I asked whether they will update the driver and got this reply:

---

Hello Bill,

We are actively testing and looking for fixes on our end for this issue yes, as of right now we do not have a specific timeframe as to when we will have a solution though I can assure you we are working hard on a fix.

Kind regards,

Linus

Macrium UK Support Team

@bmeacham - allowing that Macrium driver to function has absolutely nothing to do with the VSS issues being experienced by users in this thread.

hi, all, i had the same problem with this vss thing. i did what reflect suggests,
create a bootable flash drive with reflect on it and boot with that and then do the backup.
windows is not running so it won't interfere with the backup. works fine

There are reports (from other products having the same issue) that the installation of the May Security Update KB5089549 has eliminated this issue...

The latest MS 2nd Tuesday Security update appears to have fixed the VSS issue.

thanks for the info, i will try it

Just tried it, it works just fine.