Microsoft is investigating reports that some Windows 11 devices are failing to boot with "UNMOUNTABLE_BOOT_VOLUME" errors after installing the January 2026 Patch Tuesday security updates. [...]
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source https://www.bleepingcomputer.com/news/microsoft/microsoft-investigates-windows-11-boot-failures-after-january-updates/
source https://www.bleepingcomputer.com/news/microsoft/microsoft-investigates-windows-11-boot-failures-after-january-updates/