Microsoft has reached out to the business community, urging organizations to seek guidance on addressing a known issue related to Message Queuing (MSMQ). This problem has been causing disruptions in enterprise applications and Internet Information Services (IIS) sites.
Understanding the MSMQ Issue
MSMQ is an optional service within Windows that facilitates communication between applications over a network, particularly in enterprise settings. The current issue predominantly affects users operating on Windows 10 22H2, Windows Server 2019, and Windows Server 2016 who have recently installed specific security updates: KB5071546, KB5071544, and KB5071543, released during the December 2025 Patch Tuesday.
As Microsoft continues to investigate the matter, it has advised enterprise customers to contact their support team for strategies to temporarily mitigate the impact of this bug. The company emphasized that personal users of Windows Home or Pro editions are unlikely to encounter this issue, which primarily disrupts managed IT environments.
According to Microsoft, affected users may experience a variety of symptoms, including:
- Inactive MSMQ queues
- Applications unable to write to queues
- IIS sites failing with “insufficient resources” errors
- Misleading messages indicating “insufficient disk space or memory,” despite adequate resources being available
The root of the problem lies in recent modifications to the MSMQ security model, which have altered permissions on a critical system folder. This change necessitates that MSMQ users possess write access to a directory that is typically restricted to administrators.
Microsoft elaborated, stating, “This issue is caused by the recent changes introduced to the MSMQ security model and NTFS permissions on C:WindowsSystem32MSMQstorage folder. MSMQ users now require write access to this folder, which is normally restricted to administrators. As a result, attempts to send messages via MSMQ APIs might fail with resource errors. This issue also impacts clustered MSMQ environments under load.”
At this time, Microsoft has not provided a timeline for a fix and has not confirmed whether an emergency update will be issued or if it will wait for the next scheduled release. IT administrators facing this challenge are encouraged to reach out to Microsoft’s business support team for a temporary workaround or may need to consider rolling back the recent updates.
In a related note, Microsoft previously requested businesses to seek assistance regarding another known issue that was causing Cluster service and VM restart problems following the installation of the July 2025 Windows Server 2019 security updates.
