Microsoft Security Update Causes MSMQ Failures on Older Windows Systems

A recent Microsoft security update released in December 2025 has caused significant issues with the Message Queuing (MSMQ) service on Windows 10 and older Windows Server versions. The update introduced changes to the MSMQ security model and NTFS permissions, specifically affecting the C:\Windows\System32\MSMQ\storage folder, which now requires write access for MSMQ users. As a result, MSMQ queues may become inactive, Internet Information Services (IIS) sites can fail with resource errors, and applications may be unable to write to queues, despite system resources being available. The issue primarily impacts enterprise and managed IT environments, especially those running clustered MSMQ under load, while personal devices are largely unaffected.

Administrators have reported a range of failures, including point-of-sale systems unable to issue receipts and building fire alarm systems going offline, potentially linked to the MSMQ malfunction. Microsoft has acknowledged the problem and suggested contacting their support team for a workaround, though some users have found that uninstalling the update resolves the issue. The lack of a detailed public workaround and the critical nature of affected applications have raised concerns among IT professionals about the reliability of recent security updates and the support process for urgent enterprise disruptions.