Windows 11’s Patch Tuesday nightmare gets worse — Microsoft says some PCs might not boot

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Microsoft has acknowledged that a recent security update released on January 13th, specifically the January 2026 update, is causing some computers to fail to start. This adds to a growing list of problems users have experienced since the latest updates were released earlier this week.

The company has already issued two urgent fixes for Windows 11 to resolve significant problems caused by this month’s security updates. However, a new issue preventing some computers from starting up still hasn’t been fixed.

As a researcher, I’ve been following reports of a recent issue affecting some Windows devices. Microsoft has acknowledged that a small number of users are experiencing boot failures – specifically, a ‘UNMOUNTABLE_BOOT_VOLUME’ error – after installing the January 2026 security update, released on January 13, 2026, and subsequent updates. Essentially, affected devices display a black screen with a message indicating a problem and the need to restart, but they are unable to boot up normally and require manual recovery procedures.

Microsoft reports that people using the newest versions of Windows 11 (24H2 and 25H2) on their computers might experience a problem. They’re working on a solution, but for now, if you run into this issue, you’ll need to fix it yourself by booting into the Windows Recovery Environment and removing the January 2026 security update.

We don’t know how widespread this problem is, since most users are still able to start their computers normally. The company acknowledges a small number of reports about computers failing to boot, but hasn’t explained the cause or if there’s a way to prevent it.

Recent updates released this month as part of Patch Tuesday have caused several problems for users. Some with version 23H2 of Windows are finding their computers won’t shut down or enter hibernation, while those using versions 24H2 and 25H2 are unable to sign in when connecting remotely.

After a few days, problems surfaced that caused popular cloud apps like Outlook, Dropbox, and OneDrive to stop working. Microsoft quickly released two emergency updates to fix these critical errors. Now, with reports of some computers failing to start, it appears Microsoft will likely need to release a third emergency update to resolve this new issue as well.

I’ve been watching the fallout from January’s Windows 11 update, and honestly, it’s been pretty rough. It’s not really clear what went wrong, but it’s clear Microsoft needs to take a serious look at their development process. The quality of updates seems to have really slipped, and it feels like things are at a low point.

via Neowin

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2026-01-25 21:09