Windows 11 update causing Blue Screens of Death: What you should know

A flatscreen monitor displays the Windows 'blue screen of death' indicating a system failure.
(Image credit: dennizn/Shutterstock)

Editor's Note: Since this article was published, MSI has begun issuing BIOS updates for some of its motherboards, which it identified as the source of the problem. All updates for affected motherboards should be available by the end of September. The original article follows.

Windows 11 users should be aware that Microsoft's latest update is causing some PCs to crash and display an “UNSUPPORTED_PROCESSOR” on the dreaded Blue Screen of Death.

This is especially notable because it's reportedly happening to Windows 11 PCs that are out in the wild, so it's a threat to anyone who downloads the latest update. That's a bit worse than most crash-related Windows 11 problems we see, which typically hit users who have enrolled themselves in the Windows Insider Program to test pre-release builds of Windows 11.

Somehow this bug made it out of Microsoft's testing program and into Windows 11 update KB5029351, which was released on Tuesday (August 22) to fix a number of issues and add improvements like a new "hover" feature to the Windows 11 search bar. 

Shortly after the update was released, people began posting complaints on websites like Reddit about the update causing their PCs to lock up, crash and roll back to previous updates. These complaints chiefly mentioned PCs with MSI motherboards, and they were picked up and echoed by outlets like The Verge, which reported experiencing a similar issue firsthand with a Windows 11 PC sporting an MSI MPG Z690 motherboard.

The Windows 11 Feedback Hub is full of complaints about "UNSUPPORTED_PROCESSOR" errors wreaking havoc after the KB5029351 update. (Image credit: Future)

By Wednesday Microsoft had issued an official response on its page listing known issues with Windows 11. 

"Microsoft has received reports of an issue in which users are receiving an “UNSUPPORTED_PROCESSOR” error message on a blue screen after installing updates released on August 22, 2023 ( KB5029351) and then restarting their device," reads an excerpt of the company's response. "We are presently investigating to determine if this is an issue caused by Microsoft. We will provide an update when more information is available."

As you can see, there's no mention of what might be causing these Blue Screens of Death or when we should expect a fix. Hopefully by the time you read this it will no longer be an issue, but as of Friday (August 25) Microsoft is still investigating the problem.

What to do if you've been affected

This issue could impact anyone who has installed update KB5029351 to their Windows 11 or Windows 10 PC. If you or someone you know is experiencing crashing and seeing the "UNSUPPORTED_PROCESSOR" error message, you may be affected by this bug.

You can try to roll back the update and restore your copy of Windows to an earlier version. If you're lucky, Windows will do this itself and automatically uninstall the KB5029351 update.

If that doesn't work, you can try booting into Windows 11 Safe Mode and using the advanced options therein to do things like run repair diagnostics or restore a previous version of Windows. 

If you have an MSI motherboard, there's a good chance you need to update your BIOS to fix this issue. MSI published an explanation and a list of places to download a  BIOS update which will solve the problem, so hopefully that solves your problem!

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Alex Wawro
Senior Editor Computing

Alex Wawro is a lifelong tech and games enthusiast with more than a decade of experience covering both for outlets like Game Developer, Black Hat, and PC World magazine. A lifelong PC builder, he currently serves as a senior editor at Tom's Guide covering all things computing, from laptops and desktops to keyboards and mice. 

  • kep55
    I thought win11 was the most tested os mictosoft ever made. Who did the testing? Howard, Howard & Fine? Dr Quackenbush?