February updates break MSMQ again

Question

I know the December update had broke MSMQ. We removed this update since it broke a main feature of our accounting software. We installed the January update, no problems. But this month we installed KB5075999 and KB5075902 and we are getting the insufficient resources issue with MSMQ again. I tried all the work arounds, but the issue still persists. It wouldn't let me uninstall it. Luckily, this is on our test server, so I was able to restore the VM to how it was prior to the update. I ran the updates again just to verify, and MSMQ is busted again. I even tried writing to the message queue as a domain admin with explicit permissions and got the insufficient resources. There's nothing in the release notes for these updates, but the February security updates break MSMQ. Anybody have anything else I can try to fix this? Forgot to add that this is on Windows Server 2016. I already tried to install the OOB update, but it says it's not applicable.

Answer 1

Hello Robbie Saăyer,

You are correct that the February 2026 cumulative updates KB5075999 and KB5075902 are reintroducing the MSMQ “insufficient resources” issue on Windows Server 2016. This is consistent with what was seen in December, where MSMQ broke after the monthly rollup. The January patch cycle temporarily resolved it, but the February updates appear to have regressed the fix.

The reason you cannot uninstall KB5075999 or KB5075902 is that they are cumulative updates. Once installed, they replace the servicing stack and supersede prior rollups, so Windows Update treats them as non‑removable. The only way to roll back is exactly what you did: restore the VM snapshot or system image taken before patching.

Microsoft has acknowledged MSMQ regressions in past cumulative updates for Server 2016, but as of now there is no documented hotfix for the February 2026 cycle. The “OOB update not applicable” message you saw is expected because those out‑of‑band patches were scoped to December’s regression and not flagged for February’s cumulative.

At this point, the only supported options are:

• Keep the February updates off production systems until Microsoft releases a servicing fix.
• Monitor the Windows Server 2016 update history page and the Microsoft Update Catalog for any new OOB patches specifically targeting MSMQ.
• If you must patch for security compliance, consider isolating MSMQ workloads to servers where the February updates are not applied, and patch other roles separately.

Unfortunately, there is no registry or configuration workaround that reliably restores MSMQ functionality once the February cumulative updates are installed. The regression is within the MSMQ service binaries updated by the rollup.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

Domic Vo.

Answer 2

The symptoms described match the known MSMQ issue introduced by the December 2025 Windows security updates, which was later reintroduced/impacted again by subsequent security updates. The root cause is a change to the MSMQ security model and NTFS permissions on C:\Windows\System32\MSMQ\storage, causing MSMQ users to lack required write access and resulting in:

• MSMQ queues becoming inactive
• “Insufficient resources to perform operation” errors (including from IIS sites)
• Applications unable to write to queues
• Errors like The message file 'C:\Windows\System32\msmq\storage\*.mq' cannot be created
• Misleading logs about insufficient disk space or memory

The supported fix is not to tweak permissions manually but to install the corresponding out‑of‑band (OOB) or follow‑up updates that explicitly address the MSMQ regression for the affected OS version.

Actions to take:

1. Identify the exact OS version/build of the affected server (for example, Windows Server 2016/2019/2022 or Windows 10/11 equivalent build).
2. For that OS, install the specific OOB or follow‑up update that resolves the MSMQ issue, or any later cumulative update that supersedes it. Examples from the documented issues:
   • Windows 10 1607 / Windows Server 2016: OOB update KB5074974
   • Windows 10 1809 / Windows Server 2019: OOB update KB5074975
   • Windows 10 21H2/22H2 and related: OOB updates KB5074976 or KB5077796
   • Monthly rollup/server variants: KB5074978, KB5074980, or later
3. Obtain the update from Windows Update or, if needed, directly from the Microsoft Update Catalog as indicated in the release‑health notes.
4. After installing the appropriate OOB/follow‑up update, reboot the server and re‑test MSMQ queue operations under load and with the accounting application.

If MSMQ is still failing after the correct OOB/follow‑up update is installed, verify that the server is fully up to date with all cumulative updates released after the OOB fix date (December 18, 2025 or January 17, 2026, depending on platform). The guidance from Microsoft is to install the latest update, as it includes the MSMQ fix.

Rollback of the February security updates should only be used as a temporary mitigation on test systems; the long‑term resolution is to move to a build that includes the MSMQ fix.

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References:

• December 9, 2025—KB5071503 (Monthly Rollup)
• December 9, 2025—KB5071546 (OS Builds 19045.6691 and 19044.6691)
• December 9, 2025—KB5071505 (Monthly Rollup)
• Resolved issues in Windows 10, version 1607 and Windows Server 2016
• Resolved issues in Windows 10, version 1809 and Windows Server 2019
• Resolved issues in Windows 10, version 22H2