Windows Server administrators are reporting widespread disruptions to **Remote Desktop Services (RDS)** after applying the September 2026 cumulative updates. These critical updates, part of **Microsoft**'s regular Patch Tuesday release, are causing RDS connections to fail on **Windows Server 2019**, **2022**, and **2025** systems. Reports from various forums, including Reddit, indicate that servers initially function normally for several hours post-update. However, they subsequently begin to experience connection failures. Once affected, existing Remote Desktop sessions may become unable to disconnect or log off properly. New connection attempts often hang indefinitely before ultimately failing, severely impacting user access and administrative capabilities.  **BleepingComputer** has also received direct accounts from readers experiencing similar problems on their Terminal Servers after installing the September updates. One affected administrator noted, "All terminal servers in our environment are failing (sessions dropping, no new connections possible, only solution is a hard reset) within a day." Another administrator detailed a scenario where RDS initially worked post-update, but services crashed after the first user logged out, preventing subsequent sign-ins. For this user, a server restart did not resolve the issue, but rolling back the September update successfully restored functionality. ### Potential Deadlock Identified Further investigation by an administrator on a Server 2022 system suggests a potential underlying cause. Debugging indicated that the RDP service becomes unresponsive during user logoffs, with evidence pointing to a deadlock between Remote Desktop and the **Local Session Manager (LSM)**. "The service hangs at **RDPSERVERBASE!WDLIB_Close**, there seems to be no timeout set here. This results in a deadlock between RDP and LSM," a Reddit user reported. However, **Microsoft** has not yet confirmed this specific technical diagnosis. ### Affected Updates and Mitigation The issues are impacting multiple Windows Server versions, specifically with updates **KB5122876** for Server 2019, **KB5122882** for Server 2022, and **KB5122871** for Server 2025. While rolling back these updates appears to resolve the RDS functionality, it also removes the crucial security patches included in the September Patch Tuesday release. This places IT security professionals in a difficult position, forcing a choice between critical system access and maintaining a secure posture. **Microsoft** has acknowledged the reports and stated that it is currently investigating the issue. The company has committed to providing guidance as soon as it becomes available. In the interim, organizations are advised to monitor official channels for updates and consider the implications of deferring or rolling back these specific updates.