Remote Desktop Services might stop responding after Sept. 2026 security update

Microsoft resolved September update RDS instability with the September 14, 2026 out-of-band update and later cumulative updates.

What changed

The September 14 OOB updates KB5129194 and KB5129237 resolve RDP connection failures, sign-in problems and hangs affecting RDS, MMC, File Explorer and Windows Update.

Technical details

Microsoft marks the issue as mitigated while preparing a permanent Windows update resolution

Why it matters

RDS instability can interrupt remote access, sign-in, MMC, File Explorer and Windows Update on patched clients and servers.

Known limitations

A deallocation and restart can temporarily restore RDP access to an inaccessible virtual machine
The issue affects Windows 11, Windows 10 and Windows Server versions listed by Microsoft

Now check

Deploy the applicable September 14 OOB update or a later cumulative update
Retest RDP sessions, sign-in, MMC, RDS Licensing Diagnoser and Windows Update
Confirm temporary Group Policy mitigation handling for the affected Windows version