Windows 11 January 2026 updates may cause boot failures on some PCs. Microsoft is investigating issues linked to KB5074109.

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

Microsoft is investigating reports that some Windows 11 devices are failing to boot with "UNMOUNTABLE_BOOT_VOLUME" errors ...

This comes just hours after reports that another emergency update has been issued by Microsoft to affect other problems ...

Windows 11 runs into another disastrous bug with its latest update — Microsoft admits an 'issue in which devices are failing ...

It's not just January's one.

Microsoft is shifting focus to fixing Windows 11 performance and reliability after months of buggy updates, boot failures, ...

Microsoft is aware of an alleged issue that leaves PCs unable to boot and requires manual recovery after Windows 11 January ...

Another week, another big Windows problem.

Microsoft released unplanned updates over the weekend. They correct errors in the January patches and bring new boot certificates.

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