Administrators worldwide are facing significant challenges with Remote Desktop Services (RDS) on Windows Servers following the distribution of Microsoft’s September 2026 Patch Tuesday updates. This issue affects Windows Server versions 2019, 2022, and 2025, resulting in system freezes and connectivity problems.
Identifying the Source of the RDS Failures
The complications have been traced to cumulative updates KB5122876, KB5122882, and KB5122871, which were released as part of the latest security updates. These updates have caused session hosts to freeze, leaving Remote Desktop Protocol (RDP) connections in a perpetual ‘Connecting…’ state and preventing users from logging off smoothly.
Initial reports emerged from the r/sysadmin community on Reddit, where numerous administrators detailed identical issues across different environments, indicating a widespread problem rather than isolated incidents.
Technical Insights into the RDS Deadlock
After rebooting, affected systems typically operate normally for a few hours before issues arise, generally triggered by user session activities. New RDP attempts hang at the login phase, causing Event ID 20498 to appear in the TerminalServices-RemoteConnectionManager log, indicating prolonged connection times.
Administrators have discovered that the problem may stem from a deadlock in the RDP server base library, specifically in the RDPSERVERBASE!WDLIB_Close routine, which is executed during session termination. This deadlock results in system paralysis, requiring a hard reset to restore functionality.
Mitigation and Future Outlook
Microsoft has yet to confirm the root cause of the issue or provide an official response. Meanwhile, administrators face a dilemma as rolling back the updates can stabilize systems but also removes crucial security patches. September’s updates addressed nearly 973 vulnerabilities, including critical ones like CVE-2026-81963 and CVE-2026-69525.
As a temporary measure, some administrators have found success by disabling specific features through registry modifications, though these solutions remain unofficial. Security teams managing RDS environments should consider testing updates on non-essential systems and prepare rollback strategies while awaiting further guidance from Microsoft.
In light of the ongoing issues, system administrators are encouraged to remain vigilant and monitor for specific events indicating RDS failures, ensuring they are prepared to act swiftly should problems persist. The community continues to await Microsoft’s formal acknowledgment and a potential out-of-band fix.
