KB5078127 is being released for Windows 11 builds 25H2 or 24H2, and Microsoft says it's an 'out-of-band' patch that will fix an issue. that broke Outlook Classic (POP, PST), among other apps in Windows 11.
However, even if you didn't experience any issues after the January 2026 update, you will be offered KB5078127.
This emergency update appears as “2026-01 Update (KB5078127) (26200.7628) is available” on the Windows Update page. If you are on build 24H2, it will upgrade your operating system to Windows 11 Build 26100.7628. It takes about 5 minutes to complete the download with an internet speed of about 200mbps and another 3 minutes to install (only one restart is required).
KB5078127 is the second hotfix for Windows 11 in less than ten days. The first hotfix (KB5077744) was released on January 17th, but it was optional. However, today's hotfix is mandatory because it fixes more serious and widespread issues.
Although the press releases will range from very select to rare, I said I'd pass...because sometimes the editors hide.
