September Server Patches Break Remote Desktop — Here’s What to Do

Microsoft’s September 2026 Patch Tuesday updates are breaking Remote Desktop Services on Windows Server 2019, 2022 and 2025. If your team connects to a terminal server or RDS host to run line-of-business apps, this one needs your attention.

Admins worldwide are reporting that RDS servers work normally for a few hours after installing the updates (KB5122876, KB5122882 or KB5122871), then start dropping sessions. New connections hang and eventually fail. In some cases the only fix is a hard reset of the server. The root cause appears to be a deadlock between the Remote Desktop service and the Local Session Manager that triggers when users log off. Microsoft says it’s investigating but hasn’t issued a fix yet.

The awkward trade-off

Here’s the bind: this month’s Patch Tuesday addresses 966 security vulnerabilities, including two zero-days already being exploited in the wild. Rolling back the update — the only current workaround — removes every one of those fixes.

This is a pattern we see regularly across our client base, particularly for businesses in regional areas like the Central West or the Northern Beaches where staff connect to a central server over RDS to access accounting, practice management or CRM systems. When Remote Desktop goes down, the whole office stops. But leaving servers unpatched against nearly a thousand known flaws isn’t a real option either.

What to do right now

If you haven’t installed the September cumulative updates on your RDS hosts yet, hold off until Microsoft releases a fix. If you’ve already installed them and RDS is failing, rolling back the update restores functionality — but talk to your IT provider first about the security implications of running without this month’s patches.

For clients we manage, we’re staging the updates on non-RDS servers first and holding RDS hosts until Microsoft patches the deadlock. If you’re unsure whether your servers are affected, get in touch and we’ll check.

Need help keeping your servers patched and stable? That’s exactly what managed IT support is built for.