KB5086672: Fixed Error (Some update files are missing or have problems.)

March 31, 2026—KB5086672 (OS Builds 26200.8117 and 26100.8117) Out-of-band

This out-of-band update for Windows 11, version 25H2 and 24H2 (KB5086672) is cumulative and includes updates from previous security and non-security releases.

This update includes the improvements and features that were introduced in the March 26, 2026 non-security preview update (KB5079391), along with a fix for an installation issue that affected some devices attempting to install that update.

Improvements
This out-of-band update contains quality improvements from KB5079473 (released March 10, 2026), KB5085516 (released March 21, 2026), and KB5079391 (released March 26, 2026 - no longer offered). The following summary outlines key issues addressed by this out-of-band update. The bold text within the brackets indicates the item or area of the change.

• [Setup] Fixed: While installing the March 2026 Windows preview update (KB5079391), some devices running Windows 11, version 25H2 or 24H2, might encounter the following error:

Some update files are missing or have problems. We'll try to download the update again later. Error code: (0x80073712)

This out-of-band update is offered through Windows Update for devices running Windows 11 that have already installed KB5079473 or a later update. It is also available for manual download from the Microsoft Update Catalog.