What happened and who’s affected
Microsoft pushed out emergency out‑of‑band updates after September security patches started behaving like a grumpy gremlin in your server room. The updates caused instability in Remote Desktop Services, leading to failed RDP connections, sign‑in problems, and in extreme cases, servers that acted like very expensive paperweights.
Admins saw related tools freeze or become unresponsive — things like the Microsoft Management Console (MMC), RDS Licensing Diagnoser, File Explorer, and even the Windows Update page. Microsoft previously offered Group Policy workarounds while engineers scrambled to make a proper fix.
What Microsoft fixed (and what’s still flaky)
On September 14 Microsoft released a set of out‑of‑band updates that target the RDS breakage as well as some Hyper‑V and USB audio problems. The key updates include:
- Windows 10 21H2 and 22H2: KB5129236
- Windows 11 24H2 and 25H2: KB5129195
- Windows 11 26H1: KB5129194
- Windows Server 2019: KB5129238
- Windows Server 2022: KB5129237
- Windows Server 2025: KB5129235
These updates aim to undo the RDS trouble introduced by earlier September fixes (notably KB5122871 on Windows Server 2025 and KB5122882 on Windows Server 2022). If you temporarily uninstalled the September updates, RDP usually came back — but of course you also lost the security patches that prompted the update in the first place. So yes: trade‑offs.
The out‑of‑band packages are available through the usual channels (Windows Update, Windows Update for Business, Microsoft Update Catalog, and WSUS, depending on the OS). For some server SKUs the updates are mainly distributed via the Microsoft Update Catalog.
The fixes also address a Hyper‑V edge case where certain apps using Host Compute Service (HCS) and Plan9 shared folders made those shared directories invisible or inaccessible inside Linux guests. So fewer “where did my files go?” panic emails.
On the audio side, Microsoft fixed some multichannel USB audio problems related to 8‑channel and 3D modes. However, not all USB audio headaches are solved yet. Some USB Audio Class 1.0 devices may still fail to start or show symptoms like a Code 10 error in Device Manager, no audio output, or frozen/zeroed volume controls. Microsoft says it’s still working on the remaining audio bugs.
What you should do
- Check your environment for impacted systems and prioritize servers running RDS roles.
- Apply the out‑of‑band updates via your preferred update path (WSUS, Windows Update, or the Update Catalog) and test in a staging environment first if possible.
- If you temporarily rolled back the September updates to restore RDS, plan to reapply the emergency fixes so you don’t stay unpatched.
- For admins using Hyper‑V with Linux guests and shared folders, validate that shared mounts appear and are accessible after patching.
- If you rely on multichannel USB audio devices, test both stereo and multichannel modes; if you still see a Code 10 or no sound, document the device model and wait for the follow‑up fix or contact vendor support.
- Keep an eye on official channels for updates and be ready to deploy any follow‑up patches.
Short version: install the emergency updates once you’ve tested them, watch your audio rigs, and don’t be the person who uninstalls security patches and forgets why they did it. Your servers (and your sleep) will thank you.