Windows 11’s September 2026 update (KB5124008) shipped the movable taskbar people had been asking for since 2021, plus fixes for two zero-day vulnerabilities already being exploited in the wild. It also broke audio, Remote Desktop, and more on a meaningful number of PCs. Microsoft has already shipped one emergency follow-up, KB5129195, that fixes some of it. Here’s exactly what’s broken, what’s fixed, and what to do if you’re affected.
Check Your Build Number First
Go to Settings > System > About. If you’re on build 26200.9445 or 26100.9445, you have the original September 8 update (KB5124008) without the emergency fixes below. If you’re on 26200.9457 or 26100.9457, you already have KB5129195, the September 15 out-of-band update that resolves several of these issues. Windows Update should have installed KB5129195 automatically, but it’s worth confirming rather than assuming.
USB Audio Failures (Partially Fixed)
Some USB Audio Class 1.0 devices stop producing sound entirely after this update. Device Manager shows the error “This device cannot start (Code 10)” on the affected audio device, and the Settings sound page can become unresponsive, which makes normal troubleshooting steps useless. Increasing the volume does nothing because Windows can’t start the device in the first place.
KB5129195 fixes a related but narrower bug where multichannel audio setups, like 3D audio or 8-channel configurations, lost sound entirely; it does not fix the complete device failure described above. If your device won’t start at all, wired USB audio is currently the more likely culprit, and Bluetooth audio devices have not been reported as affected. Uninstalling or disabling the device in Device Manager will not bring the audio back, since the fault originates in the update itself rather than the driver.
Remote Desktop Services Breaking (Fixed)
After the September 8 update, some PCs couldn’t establish Remote Desktop connections at all, getting stuck at “Please wait for the Remote Desktop Configuration” or losing a responsive File Explorer and Management Console even after connecting. KB5129195 resolves this. If you rely on Remote Desktop and haven’t installed the emergency update yet, this alone is a good reason to check for updates now rather than wait for the next scheduled Patch Tuesday.
Explorer.exe Crashes and Black Desktop (Unresolved)
A smaller number of PCs are seeing Explorer.exe fail to start or crash almost immediately after sign-in, leaving a black screen with no taskbar or desktop icons. So far this mostly affects enterprise environments using profile-management tools like Citrix UPM, FSLogix, Horizon, or ProfileUnity ProfileDisks, on both 24H2 and 25H2. It has not been fixed as of KB5129195. If you hit this, open Task Manager (Ctrl+Shift+Esc, which usually still works even with a black desktop), find or create a new task, and run explorer.exe manually to restore your desktop for that session.
File History No Longer Detects Backup Drives (Unresolved)
File History, the built-in tool that keeps versioned backups of your files on an external drive, has stopped detecting connected backup drives for some users after this update. Microsoft hasn’t officially confirmed this one yet, and KB5129195 doesn’t address it. If you depend on File History, don’t assume your backups are still running; manually check under Control Panel > File History that it still lists your drive and is actively backing up, and consider a second backup method in the meantime, since a broken detection step means new file versions may not be getting saved at all.
AMD Radeon GPU Instability (Unresolved)
PCs with AMD Radeon GPUs, including the RX 6600, RX 7700 XT, RX 7800 XT, RX 7900 GRE, RX 7900 XTX, and RX 9070 XT, have reported driver timeouts, black screens, and system freezes since installing this update, including outside of gaming. Rolling back to an older GPU driver has not resolved it for affected users, which points to the Windows update rather than the driver itself. KB5129195 explicitly does not fix this. If you’re on an affected card and haven’t installed KB5124008 yet, it may be worth waiting for a further fix before updating unless you need the September security patches urgently, in which case installing them and keeping an eye on Windows Update for a follow-up is the more realistic trade-off, since skipping security updates indefinitely carries its own risk.
Shared Folders in Linux Virtual Machines (Fixed)
Some apps that run Linux virtual machines under Windows using the HCS Plan9 file-sharing feature briefly lost access to folders shared from the Windows host, even though the virtual machines themselves started normally. This mostly affected developer tools and AI coding assistants that use a Linux VM behind the scenes. KB5129195 fixes it.
Why So Many Bugs in One Update?
September’s update patched roughly 974 vulnerabilities across Microsoft’s product line, the largest single-month total on record and a sharp jump from prior months. Analysts have linked the increase to Microsoft’s expanded use of AI-assisted vulnerability discovery in its own codebase, which is surfacing far more issues than manual review historically caught. More security fixes packed into one release naturally raises the odds that some of them touch code paths in ways that weren’t fully caught in testing, which is the most plausible explanation for why this particular update has had more fallout than a typical Patch Tuesday.
What NOT to Do
Don’t uninstall KB5124008 purely to avoid these bugs unless you’re already experiencing one of them and need immediate relief; doing so also removes the fix for two zero-day vulnerabilities that are already being actively exploited, which is a worse trade-off for most people than a UI change or an intermittent bug. Don’t assume every unrelated problem on your PC this month is caused by this update either; check whether your specific symptom matches one of the patterns above before spending time troubleshooting the wrong cause.
Related: Windows 11 September 2026 Update (KB5124008 & KB5124012): What’s New and What It Fixes · Microsoft Defender’s ShieldBreak and ShieldCrash Flaws Explained
FAQ
Does KB5129195 fix all the KB5124008 bugs?
No. KB5129195, released September 15, fixes the Remote Desktop Services instability, the Linux VM shared-folder issue, and a narrower multichannel audio bug. It does not fix complete USB audio device failures (Code 10 errors), Explorer.exe/black desktop crashes, broken File History drive detection, or AMD Radeon GPU instability.
Should I uninstall KB5124008 to fix these bugs?
Generally no. KB5124008 patches two zero-day vulnerabilities already being exploited in the wild, so removing it trades a UI or stability annoyance for active security risk. It’s usually safer to install KB5129195, apply the workarounds for any remaining issue you’re hitting, and wait for Microsoft’s next fix.
My audio stopped working after this update. What should I do?
If Device Manager shows a Code 10 error on your audio device and the Settings sound page is unresponsive, this matches the confirmed USB Audio Class 1.0 bug. Microsoft hasn’t shipped a full fix yet. As a temporary workaround, try a different audio output like Bluetooth headphones, which have not been reported as affected.
Is my AMD GPU issue actually caused by this Windows update?
If you have a Radeon RX 6600, 7700 XT, 7800 XT, 7900 GRE, 7900 XTX, or 9070 XT and started seeing black screens, freezes, or driver timeouts after installing KB5124008, and rolling back your GPU driver didn’t help, the Windows update is the more likely cause rather than the driver itself. Microsoft has not shipped a fix for this as of KB5129195.