After installing the September 2026 cumulative updates—KB5122871 on Windows Server 2025 build 26100.33438 and KB5122882 on Windows Server 2022 build 20348.5622—every host in our RDS collection began experiencing severe session-state hangs. The hosts had been stable on the August updates.
New RDP connections remain stuck at "Connecting…" and eventually generate TerminalServices-RemoteConnectionManager/Admin event 20498. Existing sessions cannot disconnect or log off cleanly, Task Manager and Settings may hang, and Winlogon reports event 6005 indicating that SessionEnv is taking too long to process a disconnect notification. Normal restarts also hang, so a hard reset is currently the only way to recover a host. The issue usually returns later the same day after a session disconnect or reconnect appears to stall.
The environment includes mixed Server 2022 and Server 2025 VMware session hosts, an RD Connection Broker, MFA at logon, and third-party endpoint protection. Both updates include an RDS audio-redirection change, but neither currently lists an RDS known issue.
We are testing removal of the September updates on some hosts while leaving one updated host as a control. Has anyone seen similar behavior after KB5122871 or KB5122882, confirmed an FSLogix connection issue, or received any acknowledgment from Microsoft? Did removing the update resolve the problem?
3 Answers
A similar RDS hang was reportedly fixed on older session hosts by removing the applicable monthly update. Since these newer updates contain a comparable Remote Desktop audio-redirection change, testing an LCU rollback on an affected host seems worthwhile. Compare it with the still-patched control host and record whether the disconnect, logoff, and restart behavior returns to normal.
There does not appear to be a published RDS issue for either update yet. For testing a rollback, remember that these releases combine a servicing stack update and a cumulative update. Removing the KB through wusa may fail. Use DISM to list the installed packages, identify the LCU package, and remove that package specifically. The servicing stack portion will remain installed, which is expected.
If you use FSLogix, check that before assuming the cumulative update is solely responsible. A profile container that never finishes attaching can wedge one session, after which operations waiting on the Local Session Manager appear to pile up. While a host is hung, collect the FSLogix profile logs and verify whether the container mount completed or stalled during the disconnect/reconnect sequence.
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