December Windows Updates Break MSMQ Functionality

Microsoft's December security updates broke the Message Queuing (MSMQ) service, disrupting enterprise applications and IIS websites. The company confirmed the issue but hasn't provided a fix timeline.

MSMQ, available in all Windows versions as an optional component, provides network communication capabilities for applications and sees widespread use in enterprise environments.

The error affects Windows 10 22H2, Windows Server 2019, and Windows Server 2016 systems that installed patches KB5071546, KB5071544, and KB5071543 from the December 2025 Patch Tuesday release.

Symptoms include inactive MSMQ queues, IIS website crashes with "insufficient resources" errors, and applications unable to write data to queues. Some systems display messages about insufficient RAM or disk space despite adequate resources.

Root Cause

The problem stems from changes to the MSMQ security model that affected access rights to a critical system folder. MSMQ now requires write access to the C:\Windows\System32\MSMQ\storage directory, typically accessible only to administrators.

"The issue is caused by recent changes to the MSMQ security model and NTFS access rights for the C:\Windows\System32\MSMQ\storage folder. MSMQ users now need write access to this directory, which is usually only available to administrators," Microsoft stated. "As a result, attempts to send messages via the MSMQ API can fail with 'insufficient resources' errors. The problem also affects MSMQ cluster environments under load."

Microsoft is investigating the issue but hasn't specified whether a fix will appear in the next regular update cycle or as a separate patch. Administrators facing the problem may need to roll back the affected patches, though this creates security risks by removing December's security fixes.