September Windows Server updates break Remote Desktop Services

Recorded: Sept. 10, 2026, 9:08 p.m.

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HomeNewsMicrosoftSeptember Windows Server updates break Remote Desktop Services

September Windows Server updates break Remote Desktop Services

By Lawrence Abrams

September 10, 2026
04:34 PM
0

Windows admins report that the September 2026 cumulative updates are causing Remote Desktop Services (RDS) failures on Windows Server 2019, 2022, and 2025 systems, preventing users from connecting and, in some cases, requiring a hard reset to restore functionality.
The problems appear after installing this month's Microsoft September 2026 Patch Tuesday cumulative updates, with many admins reporting on Reddit [1, 2, 3] that RDS servers work normally for a few hours before connections start failing.
Once a server starts failing, existing Remote Desktop sessions may not be able to disconnect or log off properly. New connection attempts can also hang during the connection process and eventually fail.

Hanging Remote Desktop connectionSource: Reddit
BleepingComputer has also received reports from readers who say their Terminal Servers began experiencing similar problems after installing the September updates.
"All terminal servers in our environment are failing (sessions dropping, no new connections possible, only solution is a hard reset) within a day," one reader posted to our Patch Tuesday article.
Another reader said Remote Desktop Services initially worked normally after installing the September update but began failing after users logged out.
"We've had issues with Remote Desktop Services post September update. It works initially, but after the first log out, services crash and no further users can sign in," a Windows admin posted.
For them, restarting the server did not resolve the problem. However, rolling back the September update resolved the issues they were having.
Another administrator investigating Server 2022 reported on Reddit that the RDP service becomes unresponsive when users begin logging out and said debugging showed what appeared to be a deadlock between Remote Desktop and the Local Session Manager.
"The service hangs at RDPSERVERBASE!WDLIB_Close, there seems to be no timeout set here. This results in a deadlock between RDP and LSM," reads the post.
However, Microsoft has not confirmed this as the cause of the failures.
The reports are affecting all Windows Server releases, with administrators reporting similar problems on Server 2019 (KB5122876), Server 2022 (KB5122882), and Server 2025 (KB5122871) systems.
Admins who have rolled back the September updates say doing so restores Remote Desktop functionality. However, removing the updates also removes the security fixes included in this month's Patch Tuesday release.
BleepingComputer contacted Microsoft to ask whether it is aware of the reported Remote Desktop Services problems and whether a fix or mitigation is available but had not received a response at the time of publication.
We will update this article if Microsoft provides additional information.

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KB5122871
KB5122876
KB5122882
RDP
Remote Desktop Services
Terminal Services
Windows Server

Lawrence Abrams
Lawrence Abrams is the owner and Editor in Chief of BleepingComputer.com. Lawrence's area of expertise includes Windows, malware removal, and computer forensics. Lawrence Abrams is a co-author of the Winternals Defragmentation, Recovery, and Administration Field Guide and the technical editor for Rootkits for Dummies.

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Windows administrators have reported significant failures in Remote Desktop Services (RDS) following the installation of the Microsoft September 2026 cumulative updates, which impacted systems running Windows Server 2019, 2022, and 2025. These issues manifest as users being unable to connect to the servers, with some scenarios necessitating a hard reset to restore functionality. Reports indicate that the problems often emerge shortly after the updates are applied, with some users observing that the services functioned normally for a few hours before failing.

Specific symptoms experienced by administrators include the dropping of existing Remote Desktop sessions, the inability for users to properly disconnect or log off, and the failure of new connection attempts to initiate or complete successfully. In some instances, an administrator noted that after users logged out, the Remote Desktop Services crashed, preventing further sign-ins, and a simple server restart did not resolve the failure.

Further investigation into the technical cause revealed potential concurrency issues. One administrator reported that a deadlock appeared between the Remote Desktop service and the Local Session Manager, specifically at the RDPSERVERBASE!WDLIB_Close function, suggesting an unconfigured timeout setting contributed to the deadlock. Although Microsoft has not officially confirmed this cause of the failures, the reports indicate that the updates disrupted the critical interactions within the RDS framework.

Administrators found that rolling back the September updates was the only method reported to successfully restore full Remote Desktop functionality. However, this remediation carried the consequence of removing the security fixes included in the September Patch Tuesday release. This situation highlights a trade-off between system stability and the inclusion of security patches following these updates across the affected Windows Server operating systems.