Windows 11's Patch Tuesday nightmare gets worse

Summary

Updated 3 PM ET on January 25, 2026: For those experiencing issues with boot failures, we had to put together a whole new guide on how to fix it. While we wanted this out earlier, it takes a few hours to research and write it all up to make sure it's accurate versus just getting the news out, so we appreicate you patience, especially since it's a Sunday and most of our staff are off. — Daniel Rubino, Editor-in-Chief Microsoft has confirmed that some users might find their PC unable to boot after installing the January 2026 security update released on January 13. This is on top of the plethora of other issues that have been reported since Microsoft's disastrous Patch Tuesday updates arrived.So far, the company has released two emergency out-of-band updates for Windows 11 to address major bugs that were introduced with this month's security updates, but this latest issue that is causing PCs to fail to boot has not yet been addressed."Microsoft has received a limited number of reports of an issue in which devices are failing to boot with stop code “UNMOUNTABLE_BOOT_VOLUME”, after installing the January 2026 Windows security update released January 13, 2026, and later updates," the company has confirmed in an online bulletin (via AskWoody.) "Affected devices show a black screen with the message “Your device ran into a problem and needs a restart. You can restart.” At this stage, the device cannot complete startup and requires manual recovery steps."Microsoft says this issue is likely to impact users running Windows 11 version 24H2 and 25H2 on physical machines, and that it is exploring potential fixes and workarounds. In the meantime, if you do encounter this problem, you will need to manually recover your PC by entering the Windows Recovery Environment and uninstalling the latest January 2026 security patch.Some users might be forced to manually recover their PC by uninstalling the latest update. (Image credit: Mauro Huculak)It's unclear how common this issue is, as mo...