Microsoft rolls out second emergency Windows patch amid boot-time bug
Microsoft released a second out-of-band emergency patch (KB5078127) to fix cloud-storage access issues introduced by the January Patch Tuesday, including Outlook not opening files from OneDrive/Dropbox; however, a separate boot bug on some Windows 11 25H2/24H2 machines can cause a black screen with an UNMOUNTABLE_BOOT_VOLUME error, with no fix yet and recovery steps likely required.