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

As reported by Windows Latest, Microsoft has updated users in a support document that it is "investigating customer reports ...

Some machines are failing to start after security updates, prompting yet another Microsoft investigation Microsoft is investigating reports that its January 2026 security updates are leaving some ...

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

Microsoft has posted an online bulletin confirming that the company is investigating reports that state Windows 11's latest ...

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

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

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

In confirmed cases, Windows 11 boot failure occurs post-update, with the machine stuck at a black screen and unable to ...

In a surprising turn of events, Microsoft has confirmed that its January 2026 security update, KB5074109, is causing significant boot issues for some Windows 11 users. This latest development ...

Windows 11 had a rough 2025. We tracked the top 20 Windows 11 issues reported by Windows Latest, from failed updates to ...