Enterprise Alert: Windows 10 Update KB5071546 Breaks MSMQ Service with Insufficient Permissions

Microsoft has published documentation confirming that installing the extended security update KB5071546 on Windows 10 can cause failures in Microsoft Message Queuing (MSMQ). The issue appears after installing the December 2025 updates on Windows 10 or Windows Server 2019, where attempts to use MSMQ result in the error: System.Messaging[.]MessageQueueException: Insufficient resources to perform operation.

The root cause is a change to the MSMQ security model and NTFS permissions on the C:\Windows\System32\MSMQ\storage folder, with MSMQ users now needing write access to this directory, which is typically restricted to administrators. In many deployments MSMQ runs under IIS application pool identities, LocalService, or NetworkService accounts, which often lack such write access by default.

Microsoft states there is no workaround provided at present, leaving organisations effectively with the option to uninstall the update to restore functionality and wait for a corrective update before reinstalling the patches. according to Microsoft