Microsoft: September updates cause RDS failures on Windows Server

Microsoft has confirmed reports that the September 2026 security updates cause Remote Desktop Services (RDS) failures on Windows Server systems.

According to a release health update on Friday, this known issue impacts Windows Server 2012 and later, as well as Windows 10 and Windows 11 devices.

This confirmation follows widespread reports from Windows admins that installing this month's Patch Tuesday updates prevents users from connecting and, in some cases, requires a hard reset to restore functionality.

"In some environments, RDS might become unstable, resulting in RDP connections failing after several minutes, sign-in issues, or servers hanging at 'Please wait for the Remote Desktop Configuration'," Microsoft said on Friday.

"Related tools, including Microsoft Management Console (MMC), RDS Licensing Diagnoser, and File Explorer might also become unresponsive. Additionally, the Windows Update page might stop responding and continuously display a loading indicator."

Affected users have also found that once a server starts failing, existing Remote Desktop sessions may not disconnect or log off properly, while new connection attempts may also fail after hanging during the connection process.

Mitigation available

Microsoft now provides the following Group Policy (found under Computer Configuration > Administrative Templates), which can be used to mitigate the issue on enterprise-managed devices managed by IT departments:

• Windows 11 26H1: Windows 11 26H1 KB5124012 260912_00471 Group Policy
• Windows 11 25H2 and Windows 11 24H2: Windows 11 24H2, Windows 11 25H2 and Windows Server 2025 KB5124008 260911_19322 Group policy
• Windows 11 23H2: Windows 11 22H2 KB5122880 260912_00473 Group Policy
• Windows 10 21H2 and 22H2: Windows 10 20H2, 21H1, 21H2 and 22H2 KB5122878 260911_18476 Group Policy
• Windows Server 2025: Windows Server 2025 KB5122871 260911_18472 Group Policy
• Windows Server 2022: Windows Server 2022 KB5122882 260911_18471 Group Policy
• Windows 10 1809 and Windows Server 2019: Windows 10 1809 and Windows Server 2019 KB5122876 260911_18474 Group Policy
• Windows 10 1607 and Windows Server 2016: Windows 10 1607 and Windows Server 2016 KB5123099 260911_18473 Group Policy
• Windows Server 2012: Windows Server 2012 KB5123065 260911_18475 Group Policy
• Windows Server 2012 R2: Windows 8.1 and Windows Server 2012 R2 KB5123066 260911_18477 Group Policy

While it still works to ship a permanent fix for this issue, Microsoft said those who can't access virtual machines through RDP may be able to temporarily restore RDS connectivity by stopping and restarting the affected virtual machine.

​Windows admins have also been able to restore Remote Desktop functionality by rolling back the buggy updates. However, removing them will also remove the security fixes included in this month's Patch Tuesday release.

Microsoft fixed a similar known issue that triggered Remote Desktop and RDS connection failures in March 2025 after installing Windows updates released since January 2025.