Windows 11 KB5074109 (January 2026 Update) is causing major issues on some PCs, and Microsoft has more details to share.

A fresh wave of Windows 11 update trouble is making the rounds, and this one is about as disruptive as it gets: some PCs reportedly can’t boot after installing the latest January 2026 security update.

Neowin also notes another dark side to this latest issue. “Interestingly, Microsoft came up with a technical solution for ...

After the first update stopped PCs from shutting down or going to sleep, the latest one halts the boot-up process. Microsoft says it's investigating the problem.

It's not just January's one.

Microsoft issues second emergency patch for Windows this month - update your PC today ...

Microsoft is investigating reports of serious boot failures affecting Windows 11 devices following the January 2026 security updates. Users have reported encountering “UNMOUNTABLE_BOOT_VOLUME” errors, ...

The January update for Windows 11 has been met with considerable backlash, primarily due to reports of PCs refusing to shut down and displaying critical errors. A particularly alarming issue is the ...

Microsoft has linked recent reports of Windows 11 boot failures after installing the January 2026 updates to previously failed attempts to install the December 2025 security update, which left systems ...

Another week, another big Windows problem.