Windows administrators report that the September 2026 cumulative updates are causing Remote Desktop Services (RDS) outages on Windows Server 2019, 2022, and 2025 systems, preventing users from connecting and in some cases requiring a hard reset to restore functionality.
The issues occur after installing Microsoft’s September 2026 cumulative updates Patch Tuesday this month, with many administrators reporting on Reddit (1, 2, 3), RDS servers will function normally for a few hours before the connection fails.
Once a server fails, existing Remote Desktop sessions may not be properly disconnected or logged off. New connection attempts may also get stuck during the connection process and ultimately fail.
Source: Reddit
BleepingComputer has also received reports from readers reporting that their terminal servers experienced similar issues after installing the September updates.
“All terminal servers in our environment fail within a day (sessions are aborted, no new connections possible, only solution is a hard reset),” posted a reader in our Patch Tuesday article.
Another reader said that Remote Desktop Services initially worked normally after installing the September update, but stopped working after users logged out.
“We had issues with Remote Desktop Services after the September update. It works initially, but after the first logout, the services crash and no additional users can log in,” wrote a Windows administrator.
For them, restarting the server didn’t solve the problem. However, rolling back the September update resolved the issues.
Another administrator is examining Server 2022 reported on Reddit that the RDP service stops responding when users start logging out and that debugging showed an apparent deadlock between Remote Desktop and the local session manager.
“The service hangs at RDPSERVERBASE!WDLIB_Close, no timeout appears to be set here. This leads to a deadlock between RDP and LSM,” the post says.
However, Microsoft has not confirmed this as the cause of the outages.
The reports affect all Windows Server versions, with administrators reporting similar issues on Server 2019 (KB5122876), Server 2022 (KB5122882), and Server 2025 (KB5122871) systems.
Administrators who rolled back the September updates say this restores remote desktop functionality. However, removing the updates will also remove the security fixes included in this month’s Patch Tuesday release.
Microsoft told BleepingComputer that it is aware of the reports, is investigating and will provide guidance when it becomes available.
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