The boot issue, which Microsoft previously investigated and linked to failed December 2025 updates, affected a limited number of commercial Windows 11 devices running versions 25H2 and 24H2.

If you are encountering the 0xC1900101-0x40021 Windows 11 upgrade error, execute the solutions given below. An outdated BIOS is the primary cause of the 0xC1900101 ...

Microsoft has begun testing a new Windows 11 tool called Quick Machine Recovery, which is designed to remotely deploy fixes for buggy drivers and configurations that prevent the operating system from ...