The error code 0x800f0991 typically indicates that there are issues with the Windows Update components or that certain files required for the update are missing or corrupted. Here are some steps you can try to resolve this issue:
- Run the Windows Update Troubleshooter:
- Go to Settings > Update & Security > Troubleshoot > Additional troubleshooters > Windows Update and run the troubleshooter.
- Check for System File Corruption:
- Open Command Prompt as an administrator and run the command:
sfc /scannow. This will scan for and attempt to repair any corrupted system files.
- Open Command Prompt as an administrator and run the command:
- Use the DISM Tool:
- In the Command Prompt, run the following commands one by one:
-
DISM /Online /Cleanup-Image /CheckHealth -
DISM /Online /Cleanup-Image /ScanHealth -
DISM /Online /Cleanup-Image /RestoreHealth
-
- In the Command Prompt, run the following commands one by one:
- Reset Windows Update Components:
- You can manually reset the Windows Update components by stopping the Windows Update service, renaming the SoftwareDistribution and Catroot2 folders, and then restarting the service. This can sometimes resolve update issues.
- Perform an In-place Upgrade:
- If the above methods do not work, consider performing an in-place upgrade using an ISO file for Windows 11. This will allow you to reinstall Windows while keeping your files and applications intact.
If the issue persists, you may want to check the Microsoft Support Community for more specific guidance related to your error code.
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