Microsoft fixed the Windows 11 boot errors that appeared after the latest update

Microsoft fixed the Windows 11 boot issue

* Who: Microsoft

* What happened: After installing security updates, some computers could not boot and displayed the *UNMOUNTABLE_BOOT_VOLUME* message. The system then entered an infinite reboot loop and worked only manually.

* When:

* The error was discovered after the KB 5074109 package (released January 13).

* The patch that fixes it is included in the February Patch Tuesday update – KB 5077181, which began distributing on February 10.

How it happened

Microsoft found that the cause lay in an incorrect installation of the December 2025 security updates package. Even if you roll back the system to its pre-installation state, the device continued to behave incorrectly: attempting to install the next package caused a failure and prevented proper OS booting.

What to do

Install update KB 5077181 (the February Patch Tuesday). It fixes the boot volume mounting issue and eliminates the infinite reboot loop. After installation, the system will boot normally.