boot failure

Microsoft has confirmed a disturbing failure mode in its January 2026 security roll‑up: a limited but real set of Windows 11 devices can fail to boot after installing KB5074109, arriving as a black-screen stop with the historic UNMOUNTABLE_BOOT_VOLUME error and requiring manual recovery from the...

Microsoft has confirmed that the Windows 11 January 2026 cumulative update (tracked as KB5074109) is associated with a small but serious set of machine failures that can leave some physical PCs unable to boot, showing the UNMOUNTABLE_BOOT_VOLUME stop code and a black screen that requires manual...

Some Windows 11 systems are failing to boot after Microsoft’s January 2026 cumulative update, leaving affected PCs stuck at an early black error screen with the stop code UNMOUNTABLE_BOOT_VOLUME and forcing manual recovery or — in worst cases — a reinstall. Microsoft has acknowledged a limited...

Microsoft’s January Patch Tuesday has become a crisis for some Windows 11 users: the security rollup delivered as KB5074109 is now linked to systems that won’t boot, showing the dreaded stop code UNMOUNTABLE_BOOT_VOLUME and a black screen that leaves affected machines unusable without manual...

Microsoft released its January cumulative for Windows 11 (KB5074109) on January 13, 2026 — and within days a series of serious regressions began surfacing, from brief black screens on some Nvidia-equipped machines to full startup failures that print UNMOUNTABLE_BOOT_VOLUME (Stop Code 0xED) and...

Microsoft’s January 2026 security rollup for Windows 11 has left a small but significant subset of physical PCs unable to complete startup, producing the classic UNMOUNTABLE_BOOT_VOLUME stop code and forcing manual recovery while Microsoft investigates the cause. Background The January Patch...

Microsoft’s January 2026 cumulative for Windows 11 has turned into a high-stakes update incident: a mandatory security rollup released on January 13 is linked to a small but serious set of machines that fail to complete startup—displaying the stop code UNMOUNTABLE_BOOT_VOLUME and the message...

Microsoft has confirmed that its January cumulative update for Windows 11 is linked to a small but serious class of failures that can leave some physical PCs unbootable—often with the UNMOUNTABLE_BOOT_VOLUME stop code—forcing recovery via WinRE or, in worst cases, a clean reinstall. Background...

Microsoft has opened an engineering investigation after a subset of Windows 11 devices failed to boot following the January 13, 2026 cumulative security update, leaving some systems stuck at an early black error screen with the stop code UNMOUNTABLE_BOOT_VOLUME and requiring manual recovery to...

Microsoft’s January cumulative for Windows 11 has moved from a messy rollout to a serious support incident: after the January 13, 2026 servicing package (KB5074109) and subsequent emergency updates, Microsoft now confirms it has received a limited number of reports of physical devices that fail...

Microsoft has confirmed that its January 13, 2026 cumulative update for Windows 11 (KB5074109) is tied to a serious, if currently limited, regression that can leave physical PCs unbootable with the stop code UNMOUNTABLE_BOOT_VOLUME — a black-screen failure that requires manual recovery through...

Microsoft's January security rollup for Windows 11 has once again rattled the update ecosystem: after a series of rollback updates and emergency fixes, a subset of users who installed KB5074109 report an even darker outcome than the earlier shutdown and sleep bugs — some PCs now fail to boot...

Microsoft has opened an investigation after a subset of Windows 11 devices running the 25H2 servicing branch failed to boot following the January cumulative update, producing an early-stop error of UNMOUNTABLE_BOOT_VOLUME that in many cases left systems unusable until the offending update was...

Microsoft's first cumulative Windows 11 update of 2026 — delivered as KB5074109 on January 13 — has left a broad trail of disruption: critical security fixes were installed, but several high-impact regressions followed, forcing Microsoft into rapid damage control with out‑of‑band patches and...

A routine January Patch Tuesday rollup (KB5074109) accidentally left parts of Microsoft’s classic Outlook experience unstable for a measurable number of users, triggering freezes, lingering OUTLOOK.EXE processes, lost Sent Items and a rapid sequence of follow‑up fixes and mitigations from...