kb5074109

Microsoft has confirmed a new and potentially catastrophic side‑effect from its January 2026 Windows 11 security update: a limited but serious set of devices are failing to boot entirely after installing KB5074109, showing the stop code UNMOUNTABLE_BOOT_VOLUME and requiring manual recovery to...

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 January 13, 2026 cumulative security update—KB5074109 (OS builds 26200.7623 and 26100.7623)—has triggered a wave of stability problems across a wide range of Windows 11 devices, including black screens, failed boots, Remote Desktop authentication errors, and application hangs. While...

Microsoft has confirmed that the January 2026 cumulative security update for Windows 11 (KB5074109, delivered as OS build 26200.7623 for 25H2 and 26100.7623 for 24H2) is linked to a boot failure on a subset of physical devices that shows an UNMOUNTABLE_BOOT_VOLUME stop code and a black “Your...

The January Windows 11 security rollup is leaving a small but dangerous trail of unbootable PCs: Microsoft has acknowledged a limited number of reports where devices fail to complete startup with the stop code UNMOUNTABLE_BOOT_VOLUME (the Black Screen of Death), forcing affected systems into...

The January 2026 Windows 11 cumulative update KB5074109 has turned into one of the roughest monthly rollouts in recent memory: the update introduced multiple regressions that prompted Microsoft to tell some affected users to uninstallnstall it — and for a growing subset of those users the...

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...

Microsoft has done something it rarely does: told affected Windows 11 users to uninstall its January 13, 2026 security update (KB5074109) while engineers investigate widespread system and application breakages that followed the patch's rollout. The guidance comes after reports of severe...

A routine January Patch Tuesday update left a significant slice of Windows users temporarily unable to rely on core productivity workflows after the January 13, 2026 cumulative update (KB5074109) introduced regressions that broke parts of classic Outlook and disrupted remote access for some...

A routine Patch Tuesday release on January 13, 2026 has left a significant portion of classic Outlook users scrambling: the Windows 11 cumulative update KB5074109 and a separate Outlook Current Channel build have each introduced regressions that render parts of the traditional Outlook experience...

Microsoft’s January 13, 2026 cumulative update for Windows 11—KB5074109—has left a sizable number of users with unstable systems, prompting Microsoft and community support channels to treat uninstalling the patch as an acceptable short-term mitigation while the company works on permanent fixes...

The Jandndndndndnuary 13, 2026 Windows 11 cumulative update KB5074109 introduced a regression that can make the classic Outlook (Win32) client hang, fail to exit cleanly, and mis-handle POP/PST workflows — a problem that has prompted Microsoft to advise temporary workarounds, urged some users to...

Microsoft has confirmed a fresh wave of regressions tied to the January Patch Day security updates: some applications may stop responding or report errors when opening or saving files stored in cloud-synced locations such as OneDrive or Dropbox, Outlook Classic profiles that store PSTs on...

Windows 11 users are again facing a fresh wave of patch-related breakage: a January 13, 2026 cumulative update (KB5074109) introduced a regression that can make apps unresponsive or fail when opening or saving files on cloud‑backed storage such as OneDrive and Dropbox — and the fallout has...

Microsoft’s January security roll-up for Windows 11, released as KB5074109 on January 13, 2026, has left a swath of classic Outlook users with a client that hangs, fails to close cleanly, and in some reported cases does not record sent messages — behavior that can lead to lost or unsynced mail...

Microsoft’s January cumulative update for Windows 11, shipped as KB5074109 on January 13, 2026, introduced important security and platform fixes — and promptly created a raft of configuration‑dependent regressions that left some users with brief black screens, a broken classic Outlook experience...

Microsoftosoft’s January cumulative update for Windows 11, published as KB5074109 on January 13, 2026, delivered a heavy bundle of security fixes and an NPU-related battery optimization—but it also coincided with a wave of high-impact regressions that have left gamers and some enterprise...

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...

Millions of Windows gamers woke up to worse frame rates and unexplained stutters after January’s cumulative, and the fastest way back to smooth play is methodical: confirm the cause, update or reinstall the GPU driver cleanly, and only use Windows rollback as a last‑resort temporary step while...