KB5086672

Microsoft has released an out-of-band update KB5086672 for Windows 11, versions 24H2 and 25H2. This emergency fix addresses a critical issue where installing the previous update KB5079391 resulted in error 0x80073712, related to missing or corrupted update files. The new patch is distributed as a cumulative package that includes all current security fixes and improvements from previous March updates.

• Fix for error 0x80073712. Resolved an issue where installing the preliminary March 2026 update KB5079391 on devices with Windows 11 versions 25H2 and 24H2 caused the system to interrupt installation with a message about missing or corrupted update files.
• Cumulative nature of the update. KB5086672 (Build 26200.8117) includes all security fixes and improvements from security update KB5079473 (from March 10, 2026), out-of-band update KB5085516 (from March 22, 2026), and preliminary update KB5079391 (from March 26, 2026, which is no longer available for separate download).
• Automatic delivery via Windows Update. The update is distributed through Windows Update for devices with Windows 11 that already have KB5079473 or newer installed. If you previously installed earlier updates, only the new changes contained in this package will be downloaded and installed, saving bandwidth and time.
• Availability in the Microsoft Update Catalog. The KB5086672 package is also available for manual download from the official Microsoft Update Catalog for users who prefer to install updates offline or maintain multiple computers in a corporate network.

To install cumulative update KB5086672 via Windows Update, go to Settings > Windows Update and click the Check for updates button. The system will automatically detect the available package and offer to download it. A system restart is required to complete the installation. After the update, the Windows 11 build number will change to 26200.8117.

How the new features work:

Fix for error 0x80073712: The Windows Component-Based Servicing (CBS) checks component store integrity. When manifest hashes mismatch, the system fetches missing fragments from Trusted Installer cache, resets transaction flags, and re-evaluates file versions against the current baseline, resolving corruption without full reinstallation.

Cumulative nature of the update: A single LCU package contains all previous fixes as a unified binary set with strictly incremented versions. The servicing stack compares each file’s version to the installed one and applies only newer files, treating KB5079473, KB5085516, and KB5079391 as one atomic update.

Automatic delivery via Windows Update: Windows Update Agent requests only the byte difference between current and target build. The server compresses changed blocks using differential compression algorithms, then the local update collector applies them atomically, preserving only new changes and saving bandwidth.

Availability in the Microsoft Update Catalog: The signed CAB file contains a trusted certificate chain. Manual installation via dism /add-package or wusa.exe verifies signature, architecture, and kernel version before unpacking files into C:\Windows\SoftwareDistribution without contacting Windows Update.

The last 10 Windows updates: