Windows 11 KB5077181 Update Fixes Boot Failures Caused by Failed Installation
Microsoft Resolves Critical Windows 11 Issue
Microsoft has resolved a critical issue affecting some Windows 11 commercial systems, where devices would fail to boot due to a problem with recent security updates.
Issue Description
The issue, which was linked to a failed December 2025 update, has been fully resolved in the February 2026 Patch Tuesday update, specifically in the Windows 11 KB5077181 security update.
The problem, which affected a limited number of commercial Windows 11 devices running versions 25H2 and 24H2, caused systems to display a black screen with an “UNMOUNTABLE_BOOT_VOLUME” error message after installing the January 13, 2026, security update KB5074109 or later updates. This error rendered the systems unbootable, requiring manual recovery to restore functionality.
According to Microsoft, the issue was caused by the failed installation of the December 2025 security update, which left devices in an improper state. When subsequent updates were attempted, the system would become unbootable.
Resolution and Recommendations
Microsoft initially released an initial resolution in the optional non-security preview update KB5074105 on January 29, 2026, which helped prevent the issue from occurring on devices that had not yet encountered the problem. However, devices that became unbootable before the fix was released may still require additional remediation.
The company advises enterprise customers whose devices remain affected to contact Microsoft Support for Business for assistance restoring system stability. Microsoft has confirmed that the issue is fully resolved in the Windows 11 KB5077181 update and later updates, stating that “this issue is fully resolved in the Windows security update released on February 10, 2026 (the Resolved KBs listed above), and later updates.”
It is worth noting that Microsoft did not publicly share this advisory, despite doing so for other known Windows issues. Enterprise customers who have been impacted by this issue should take immediate action to ensure their systems are updated and stable.
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