Microsoft September Updates Cause Remote Desktop Services Failures

Microsoft has confirmed that its September 2026 security updates are causing widespread Remote Desktop Services (RDS) failures across multiple operating systems, including Windows Server, Windows 10, and Windows 11.

The issue, identified following widespread reports from system administrators, can lead to unstable RDP connections, sign-in failures, or servers hanging indefinitely at the “Please wait for the Remote Desktop Configuration” stage. Beyond connection issues, Microsoft noted that essential administrative tools such as the Microsoft Management Console (MMC), File Explorer, and the RDS Licensing Diagnoser may become unresponsive.

Affected Systems and Impact

The bug impacts Windows Server 2012 and all subsequent versions, as well as various iterations of Windows 10 and Windows 11. In some environments, the Windows Update page itself has been reported to stop responding, displaying a continuous loading indicator.

Users experiencing these failures may find that existing Remote Desktop sessions fail to disconnect or log off properly, while new attempts to connect often hang during the initial connection process.

Mitigation and Workarounds

Microsoft has released specific Group Policy settings to mitigate the issue for enterprise-managed devices. The required policy and associated knowledge base (KB) references vary depending on the version of the operating system:

• Windows 11 26H1: KB5124012
• Windows 11 25H2, 24H2, and Windows Server 2025: KB5124008
• Windows 11 23H2 and 22H2: KB5122880
• Windows 10 21H2 and 22H2: KB5122878
• Windows Server 2022: KB5122882
• Windows Server 2019 and Windows 10 1809: KB5122876
• Windows Server 2016 and Windows 10 1607: KB5123099
• Windows Server 2012 and 2012 R2: KB5123065 and KB5123066

For administrators managing virtual machines, Microsoft suggests that stopping and restarting the affected VM may temporarily restore RDS connectivity. While rolling back the buggy updates is an alternative to restore functionality, Microsoft warns that doing so will also remove the security fixes included in the September Patch Tuesday release.

This is not the first time a similar issue has surfaced. Microsoft previously addressed a comparable problem in March 2025, which also triggered Remote Desktop and RDS connection failures following the installation of updates.