servicing chain

  1. Windows 11 UNMOUNTABLE_BOOT_VOLUME: December rollback and January KB5074109 boot failures

    Microsoft has confirmed that a chain of updates — a failed December 2025 security update that left some machines in an “improper state,” followed by the January 13, 2026 cumulative update (KB5074109) — is responsible for a limited but serious set of Windows 11 boot failures that present as...