Microsoft has halted the rollout of the Windows 11 KB5079391 optional preview update after it caused installation issues on certain PCs. The update, intended for versions 25H2 and 24H2, is currently under internal investigation to determine the root cause of the problem.
The company noted that the update will not resume its rollout until the underlying issues are resolved. In a worst-case scenario, the KB5079391 update may never be released again.
The optional update was briefly made available on March 26. However, it was only offered for about an hour or two before the rollout was stopped due to the discovery of a last-minute bug.
Users affected by the bug experienced an installation error loop. Specifically, the Windows Update page displayed the error code 0x80073712 when attempting to install the software.
This specific error code indicates that assembly files required for the update are missing from the WinSxS folder. Affected devices displayed a message stating that some update files were missing or had problems, accompanied by a prompt reading, “We’ll try to download the update again later. Error code: (0x80073712).”
Microsoft confirmed the pause in a statement, noting, “Rollout of this update is temporarily paused due to installation error 0x80073712.” The company further explained that they temporarily limited the update’s availability to prevent additional impact while investigating the issue.
As of March 28, 2026, the KB5079391 update remains unavailable for download. The decision to completely pull a Windows update is relatively rare for Microsoft, suggesting the installation issues were widespread.
This installation failure follows a recent promise made by Microsoft nine days prior to make Windows 11 a better operating system and to improve the overall Windows Update experience.
Despite internal work underway to fulfill this promise, recent updates have introduced unexpected problems. Prior to the KB5079391 error loop, another recent Windows update broke Microsoft account sign-in functionality for inbox applications.