Microsoft has confirmed a significant regression in its December 2025 cumulative updates that breaks Microsoft Message Queuing (MSMQ) functionality across multiple Windows versions. The issue, affecting Windows 10, Windows 11, and Windows Server installations, renders MSMQ queues inactive and prevents message processing in enterprise environments that rely on this legacy messaging technology for critical business operations.

The Technical Breakdown: What Went Wrong?

The December 9-12, 2025 cumulative updates—including KB5071546 for Windows 10 22H2 ESU builds—introduced changes to NTFS permissions handling that inadvertently broke MSMQ functionality. According to Microsoft's official acknowledgment, the updates modified how system components interact with file system permissions, specifically affecting the MSMQ service's ability to access required registry keys and queue storage locations.

Search results confirm that MSMQ, while considered a legacy technology, remains crucial for many enterprise applications, particularly in financial services, healthcare, and manufacturing sectors where message queuing provides reliable asynchronous communication between distributed systems. The technology, first introduced with Windows NT 4.0, continues to support numerous legacy applications that haven't been migrated to modern messaging platforms like Azure Service Bus or RabbitMQ.

Impact Assessment: Who's Affected and How?

Organizations running Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, Windows Server 2022, Windows 10, and Windows 11 with the December 2025 updates installed are experiencing MSMQ failures. The symptoms include:

  • Inactive message queues that appear empty but contain unprocessed messages
  • MSMQ service failures or crashes during startup
  • Applications unable to send or receive messages through MSMQ
  • Event log errors related to permission denials for MSMQ components
  • Queue corruption in some severe cases
Enterprise administrators report that the issue manifests differently depending on the specific Windows version and whether MSMQ was installed before or after applying the updates. Systems with MSMQ installed prior to the update appear to experience more severe disruptions, while fresh installations may fail completely.

The Root Cause: NTFS Permission Changes

Technical analysis reveals that the December 2025 updates altered how Windows handles NTFS permissions for certain system services. MSMQ relies on specific registry keys under HKEYLOCALMACHINE\SOFTWARE\Microsoft\MSMQ and file system locations (typically C:\Windows\System32\msmq) for configuration and queue storage. The permission changes prevent the MSMQ service from accessing these resources, effectively crippling its functionality.

Search results indicate this isn't the first time Microsoft updates have broken MSMQ. Similar issues occurred with previous updates, highlighting the challenges of maintaining compatibility with legacy technologies while implementing security improvements. The current regression appears particularly severe because it affects the fundamental permission structure that MSMQ depends on for operation.

Microsoft's Response and Official Workarounds

Microsoft has acknowledged the issue and provided temporary workarounds while a permanent fix is developed. The company's official guidance includes:

Option 1: Manual Permission Restoration Administrators can manually restore permissions to the affected registry keys and file system locations:

  1. Open Registry Editor and navigate to HKEYLOCALMACHINE\SOFTWARE\Microsoft\MSMQ
  2. Right-click the MSMQ key, select Permissions
  3. Add the \