Windows administrators are currently facing significant challenges following the installation of the September 2026 cumulative updates, which have led to failures in Remote Desktop Services (RDS) across Windows Server versions 2019, 2022, and 2025. Users are finding themselves unable to connect, with some situations necessitating a hard reset to regain functionality.
Impact of September Updates
The issues emerged shortly after the rollout of Microsoft’s Patch Tuesday updates for September 2026. A wave of reports on platforms like Reddit indicates that RDS servers initially function without issue for a few hours, only to experience connection failures thereafter. Once a server begins to falter, existing Remote Desktop sessions may struggle to disconnect or log off correctly, while new connection attempts can become stuck and ultimately fail.
Source: Reddit
Readers of BleepingComputer have echoed similar sentiments, describing their Terminal Servers as encountering comparable issues post-update. One user lamented, “All terminal servers in our environment are failing (sessions dropping, no new connections possible, only solution is a hard reset) within a day,” highlighting the urgency of the situation.
Another administrator noted that while Remote Desktop Services operated smoothly immediately after the September update, problems arose 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,” they shared. In this case, a server restart did not alleviate the problem, but rolling back the September update successfully restored functionality.
Further investigation by another administrator revealed that the RDP service becomes unresponsive during user logouts, suggesting a potential 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,” the post detailed.
Despite the growing number of reports, Microsoft has yet to confirm the underlying cause of these failures. The issues are widespread, affecting all Windows Server releases, with administrators noting similar problems across Server 2019 (KB5122876), Server 2022 (KB5122882), and Server 2025 (KB5122871).
While some administrators have successfully restored Remote Desktop functionality by rolling back the September updates, this action also removes the important security fixes included in this month’s Patch Tuesday release. Microsoft has acknowledged the situation and is currently investigating the matter, promising to provide guidance as it becomes available.
