2026-11 Security Update (KB5132061) (26300.9974) - Install error - 0x800f0993

Check KB5132061’s Windows 11 26H2 prerequisites first, then install its standalone packages in the documented order rather than repeating restarts.

1. Verify the required servicing stack

KB5132061 targeting build 26300.9974 is the Windows 11 26H2 package. For 26H2, Microsoft requires:

• An update released on or after September 22, 2026, such as KB5124010.
• Servicing Stack Update (SSU) 26100.9539 or later. ^1^

Open Start, type Command Prompt, select Run as administrator, and run:

DISM /Online /Get-Packages | findstr /i "ServicingStack"

Check the version in the returned Package Identity:

• 26100.9539 or later: continue to step 2.
• Earlier than 26100.9539: return to Settings > Windows Update > Check for updates and install all earlier available updates first.
• Also check Settings > Windows Update > Update history for an update dated September 22, 2026 or later.

2. Install KB5132061 manually

For an x64-based PC—check Settings > System > About > System type—Microsoft’s Catalog instructions require these two .msu files to be installed individually in this order:

1. windows11.0-kb5043080-x64_953449672073f8fb99badb4cc6d5d7849b9c83e8.msu
2. windows11.0-kb5132061-x64_aedc878e9e078df2ec7e2cfb98dd5b21831cdbcc.msu

Download both from the Catalog section of the KB5132061 page, double-click the first file, let it finish, and then double-click the second. If Windows reports that the checkpoint update is already installed, continue with KB5132061. Restart after both installers finish. ^2^

For an Arm-based PC, do not use the x64 files; select the package matching the device architecture.

Microsoft currently lists no known issues for KB5132061, and the Windows 11 26H2 release-health page does not list 0x800f0993 as a recognized issue for this update. ^1^ ^3^

3. If the standalone installer also fails

Repair the Windows component store and protected system files. In Command Prompt (Administrator), run these one at a time:

DISM.exe /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Wait for DISM to report that restoration completed successfully and for SFC to reach 100%. Restart once, then retry the ordered standalone installation. Microsoft documents these commands as the system-file repair path for Windows Update failures. ^4^

4. Non-destructive recovery fallback

If both manual installation and component repair fail:

1. Back up important files.
2. Open Settings > System > Recovery.
3. Under Fix problems using Windows Update, select Reinstall now.
4. Keep the computer connected to power and the internet.
5. Restart when prompted, then check for updates again.

This reinstalls the same Windows version, repairs system files and components, and preserves installed apps, files, and settings. ^5^

If Fix problems using Windows Update is unavailable or the repair reinstall fails, use the Get Help app to contact Microsoft Support and provide the KB number, error 0x800f0993, current output from the servicing-stack command, and the result from the standalone installer.

References

1. November 10, 2026—KB5132061 (OS Builds 26300.9974, 26200.9974 and 26100 ...
2. Catalog
3. Windows 11, version 26H2 known issues and notifications
4. Windows 11
5. Fix issues by reinstalling the current version of Windows | Microsoft Support