Microsoft has begun rolling out Windows 11 KB5086672, an out-of-band update designed to replace a recently pulled optional patch. The new release comes with several notable improvements and addresses the widespread installation issues that plagued its predecessor.
The previous patch, known as the March 2026 optional update or KB5079391, was initially released on March 26. However, it failed to install on numerous personal computers, prompting the rare decision by Microsoft to withdraw it.
Users attempting to install the original March update encountered vague error messages, ultimately leading to a complete installation failure. The exact number of affected devices remains unknown, but the problem was significant enough to halt the rollout entirely.
According to a statement from Microsoft, KB5079391 contained a bug that trapped devices in a continuous loop of downloading and installing. This process eventually crashed, displaying error code 0x80073712.
Error 0x80073712 typically indicates that certain necessary Windows Update files are missing. Microsoft officially paused the update on March 28 to investigate the problem and limit further impact on users.
On the last day of March, the company introduced the replacement update, officially labeled “2026-03 Update (KB5086672) (26200.8117)”. Because it was released outside of Microsoft’s standard schedule, it is classified as an out-of-band release.
Windows 11 KB5086672 directly resolves the installation errors caused by the earlier optional update. Users who missed the initial release can now download the new build, which contains all the new features originally intended for the March rollout.
The newly released update will also appear for users who successfully installed the original KB5079391 patch. Despite this, users with a correctly installed version of the prior update likely do not need to install KB5086672.
Because the new release acts simply as a revision to the March optional update, users who already have the working version will not notice any differences on their PCs.
Microsoft notes that optional preview updates like KB5086672 are officially designed for production use. This distinguishes them from Windows Insider Preview builds, which are strictly intended for beta testing purposes.