Microsoft Emergency Update for Windows 10 MSMQ Disruption Affecting IIS Sites

Microsoft released an emergency out-of-band update to address a critical issue with Message Queuing (MSMQ) on Windows 10 systems, which emerged after the December 9, 2025, security updates. The bug caused MSMQ queues to become inactive, preventing applications from writing to queues and resulting in error messages related to insufficient resources, disk space, or memory. The problem was particularly severe in enterprise and clustered MSMQ environments, especially those running Internet Information Services (IIS) sites that rely on MSMQ for asynchronous processing, leading to potential service disruptions.

The out-of-band update (KB5074976) is available via the Microsoft Update Catalog and is not distributed through Windows Update or WSUS. Microsoft recommends that affected organizations, especially those with managed IT infrastructures or Azure-hosted devices, prioritize deploying the update and ensure the latest servicing stack update is installed to avoid deployment issues. Regular users with Windows Home or Pro editions are largely unaffected. Administrators are advised to test the patch in staging environments before production rollout to ensure stability and prevent further complications.