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

Another week, another big Windows problem.

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

A fresh wave of Windows 11 update trouble is making the rounds, and this one is about as disruptive as it gets: some PCs reportedly can’t boot after installing the latest January 2026 security update.

微软确认 1 月更新导致 Windows 11 突然黑屏死机然后无法启动，显示 BOOT 方面的损坏需要执行手动恢复步骤。BOOT 方面的错误代码通常意味着系统严重故障、BIOS 或启动 / ...

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

You will also need a TPM.