KB5078127: This OOB update includes quality improvements

January 24, 2026—KB5078127 (OS Builds 26200.7628 and 26100.7628) Out-of-band

Improvements
This OOB update includes quality improvements. This update is cumulative and includes security fixes and improvements from the January 13, 2026, security update (KB5074109) and the out-of-band update (KB5077744) from January 17, 2026, in addition to the following:

• [File System] Fixed: After installing the Windows update released on and after January 13, 2026, some applications became unresponsive or encountered unexpected errors when opening files from or saving files to cloud-based storage, such as OneDrive or Dropbox. In certain Outlook configurations that store PST files on OneDrive, Outlook may hang and fail to reopen unless the process is terminated or the system is restarted. Users may also see missing sent Items or previously downloaded emails being re‑downloaded.

This update is offered through Windows Update for devices running Windows 11 that have already installed KB5074109 or KB5077744. It is also available for manual download from the Microsoft Update Catalog.