Windows Update Install Error - 0x800700c1

Question

I've followed many forums and have taken those troubleshooting steps, but no luck. I'm hoping someone can help me directly. I have Windows 11.

Answer 1

Please run this fixlist. It sources the system modules from my GitHub page.

• Download the Farbar Scanner - https://downloads.malwarebytes.com/file/mbst-frst64 (FRST64.exe)
• Download fixlist.txt
• Save Fixlist.txt to the same folder as FRST64.exe.
• Launch the Farbar Scanner tool and click "Fix".
• Restart Windows when prompted.
• Upload the output log file (FixLog.txt) to your OneDrive.

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Note: If Microsoft Edge or Chrome mislabels the Farbar Scanner executable as PUA/malware, choose to keep it by tapping … in the bottom bar, choosing Keep, and then choosing Keep anyway in the dialog that appears.

See this screenshot:https://learn.microsoft.com/en-us/deployedge/media/microsoft-edge-security-download-interruptions/dowload-was-blocked.png. It's a safe tool used in most antimalware forums.

Answer 2

The error code 87 has been fixed. Please see if you can install updates.

Answer 3

Thankfully I was able to download 2 of the updates, unfortunately 1 is still unable to download as in the following images:

Answer 4

The 2025-05 quality update may have been applied already.

Please run "winver.exe" and note the OS build number. Post it here.

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Note:

Check for 24H2 gated blocks, if any. Open admin Command Prompt and run these two commands:

schtasks.exe /Run /TN "\Microsoft\Windows\Application Experience\Microsoft Compatibility Appraiser"

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CompatTelRunner.exe -m:appraiser.dll -f:DoScheduledTelemetryRun

It should take three to five minutes. Then, run the following command:

REG QUERY "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\TargetVersionUpgradeExperienceIndicators" /s

Post the output here.

Answer 5

I'm not sure I did the second part right so ill send it all below