Windows update installation

Ensure the Windows drive has at least 20 GB free and disconnect any VPN before retrying Windows 11 26H2, because Microsoft associates error 0x800f0922 with insufficient storage, Windows Update connectivity, or insufficient free space in the System Reserved partition.^1^

Since the troubleshooter and a normal restart have already failed, proceed with these new steps.

1. Check storage and disconnect VPN

1. Open File Explorer → This PC.
2. Check the free space shown for Local Disk (C:).
3. If it is below 20 GB, open Settings → System → Storage → Cleanup recommendations.
4. Review Temporary files, Large or unused files, and Unused apps, then remove only items you do not need.^2^
5. Disconnect any work or personal VPN completely.
6. Open Settings → Windows Update → Check for updates, then retry 26H2.

Do not delete Previous Windows installation unless you accept losing the ability to return to the previous Windows version.

2. Clear the Windows Update download cache

A damaged or incomplete download can persist across ordinary restarts.

1. Press Windows key + R, enter services.msc, and select OK.
2. Right-click Windows Update, then select Stop.
3. Open File Explorer and browse to:

      C:\Windows\SoftwareDistribution
   

4. Delete the contents inside that folder, but not the SoftwareDistribution folder itself.
5. Return to Services, right-click Windows Update, and select Start.
6. Restart the PC, then select Settings → Windows Update → Check for updates.^1^

This removes downloaded update files; Windows Update will download fresh copies.

3. Verify that the 26H2 servicing path applies

Press Windows key + R, enter winver, and check the currently installed version.

• If it is 24H2 or 25H2, 26H2 is installed as an enablement package.
• The device must have KB5124010 (OS build 26100.9546) or a later cumulative update installed first.
• The 26H2 enablement package is offered through Windows Update, not Microsoft Update Catalog.^3^

Check Settings → Windows Update → Update history for the prerequisite. If it is missing, install all available cumulative updates before retrying 26H2.

4. Repair the current Windows installation

If 0x800f0922 persists, use Windows 11’s nondestructive repair reinstall:

1. Back up important files.
2. Connect the PC to power and the internet.
3. Open Settings → System → Recovery.
4. Under Fix problems using Windows Update, select Reinstall now.
5. Select OK, allow the repair version to download and install, and restart when prompted.
6. Return to Settings → Windows Update and retry 26H2.

This reinstalls the current Windows version, repairs system files and components, and preserves installed apps, personal files, and settings.^4^

If Fix problems using Windows Update is absent, the PC may be managed by work or school policies, or may not have the required February 2024-or-later servicing update. In that case, an administrator must address the update policy or servicing prerequisites.^4^

References

1. Windows 11
2. Free up drive space in Windows
3. KB5121794: Feature update to Windows 11, version 26H2 by using an ...
4. Fix issues by reinstalling the current version of Windows