Windows 11 KB5074109 (January 2026 Update) is causing major issues on some PCs, and Microsoft has more details to share.

Windows 11 January 2026 updates may cause boot failures on some PCs. Microsoft is investigating issues linked to KB5074109.

Round and round we go.

Microsoft is shifting focus to fixing Windows 11 performance and reliability after months of buggy updates, boot failures, and growing user frustration.

Microsoft is investigating reports that some Windows 11 devices are failing to boot with "UNMOUNTABLE_BOOT_VOLUME" errors ...

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Microsoft has confirmed that the boot failures with its January 2026 Windows 11 update are limited to “commercial” PCs and happened due to the December 2025 update failing to install and PCs being ...

In a surprising turn of events, Microsoft has confirmed that its January 2026 security update, KB5074109, is causing significant boot issues for some Windows 11 users. This latest development ...

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 ...

After the first update stopped PCs from shutting down or going to sleep, the latest one halts the boot-up process. Microsoft ...

The fix is for a bug that prevents some systems from shutting down, while another bug that prevents hibernation has no ...