Microsoft is investigating reports that some Windows 11 devices are failing to boot with "UNMOUNTABLE_BOOT_VOLUME" errors after installing the026 Patch Tuesday security updates.
Windows 11 KB5074109 (January 2026 Update) is causing major issues on some PCs, and Microsoft has more details to share.
XDA Developers on MSN
Microsoft confirms that a stack of bad Windows updates is causing boot issues
It's not just January's one.
Microsoft is investigating reports of serious boot failures affecting Windows 11 devices following the January 2026 security ...
Microsoft has linked recent reports of Windows 11 boot failures after installing the January 2026 updates to previously failed attempts to install the December 2025 security update, which left systems ...
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