94/69 Tuesday, February 17, 2026
Microsoft has announced a fix for a Windows 11 system error that caused devices to display the “UNMOUNTABLE_BOOT_VOLUME” message or become stuck on a black screen prompting a restart, preventing users from accessing their systems. The issue primarily affected commercial (enterprise) devices following the installation of security updates earlier this year. The problem has now been officially resolved through the February 2026 Patch Tuesday update, released under KB5077181, restoring system stability.
The root cause was traced back to a faulty update installation dating back to December 2025, which left systems in an inconsistent state. When subsequent updates were installed again in January and February, the conflict caused system failures. The issue specifically impacted Windows 11 versions 24H2 and 25H2 running on physical enterprise devices. To remediate the problem, system administrators are advised to verify and install KB5077181 or a later update as soon as possible. However, for devices that are already unable to boot, installing the update alone may not be sufficient-system recovery procedures or direct engagement with Microsoft Business Support may be required.
