Multiple Windows 11 Update error - Install error - 0x800700c1

Simon Frömmer 20 Reputation points
2026-03-04T07:48:31.9533333+00:00

Hello,

I am trying to update to Windows 11, version 25H2, but I am getting an Install error - 0x800700c1 when trying to update.
It mostly tries to "correct" this by trying to install older, missing updates, but these fail as well with the same error:

  • 2025-10 Cumulative update for .NET Framework 3.5 and 4.8.1 for Windows 11, version 23H2 for x64 (KB5066133)
  • Windows 11, version 24H2

I think somewhere down the line, some older update failed and this triggered some cascading effect for newer updates.

My current image version is 10.0.22631.5768

My current version of windows is 23H2, build 22631.5768

I have tried a simple restart, running Windows Update Troubleshooter, the repair update, but those updates still fail.
From time to time

I tried running dism.exe /Online /Cleanup-image /Restorehealth via CMD as admin but I get the following error:

The source files could not be found.

Use the "Source" option to specify the location of the files that are required to restore the feature. For more information on specifying a source location, see https://go.microsoft.com/fwlink/?LinkId=243077.

The DISM log file can be found at C:\Windows\Logs\DISM\dism.log

Screenshot below (using the dutch version of windows)

I've tried an in‑place upgrade with the latest 25H2 ISO from windows, but that installation failed as well

User's image

Windows for home | Windows 11 | Windows update
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Answer accepted by question author
Ramesh 181.2K Reputation points Volunteer Moderator
2026-03-04T09:11:01.8566667+00:00

Here's the fix, based on the DISM log.

  • Download SFCFix.exe by niemiro of Sysnative forums, and save this to your Desktop.
  • Download the file, SFCFix.zip, and save this to your Desktop. Ensure that this file is named SFCFix.zip - do not rename it.
  • On your Desktop, you should see two files: SFCFix.exe and SFCFix.zip. Drag the file SFCFix.zip onto the file SFCFix.exe and release it. See illustration image
  • When you see the prompt "Will you allow SFCFix to communicate with Sysnative servers?", type "n" for no. Press Enter to continue.
  • SFCFix will now process the script. It will take some time to complete. Upload the output file SFCFix.txt to your OneDrive.
  • Restart Windows and attempt to install updates.

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  1. GsN5034 - IA 76,570 Reputation points Independent Advisor
    2026-03-04T09:15:46.4466667+00:00

    Hello, thank you for reaching out to Microsoft Q&A.

    If you are still encountering issues after following the AI-generated suggestions, please try performing an in-place upgrade.

    To do this:

    1. Download the Windows 11 ISO file from the official Microsoft website. https://www.microsoft.com/en-us/software-download/windows11 Select: User's image
    2. Once the download is complete, mount the ISO file.
    3. Double-click Setup.exe to begin the installation.
    4. This will prepare the Windows Setup screen.
    5. Follow the on-screen instructions and choose to keep your personal files and apps when prompted.

    All of your files, apps and settings will be preserved during the upgrade.

    Let me know if you need any further assistance.

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  3. Ramesh 181.2K Reputation points Volunteer Moderator
    2026-03-04T08:05:19.8333333+00:00

    Please upload the following log file in your next reply.

    C:\Windows\Logs\DISM\dism.log

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  4. AI answer

    2026-03-04T07:49:00.74+00:00

    Error 0x800700c1 and the DISM message about missing source files indicate corrupted or missing system/update components. Use supported repair methods and, if needed, an in‑place upgrade to move to 24H2/25H2.

    1. Run the Windows Update troubleshooter again
    • Go to Start > Settings > System > Troubleshoot > Other troubleshooters.
    • Run Windows Update and apply any fixes it suggests.
    1. Reset Windows Update components This clears and recreates the SoftwareDistribution and Catroot2 folders, which often fixes repeated update failures.
    2. Open Command Prompt as administrator.
    3. Run these commands one by one, pressing Enter after each:
      • net stop bits
      • net stop wuauserv
      • ren %systemroot%\softwaredistribution softwaredistribution.bak
      • ren %systemroot%\system32\catroot2 catroot2.bak
      • net start bits
      • net start wuauserv
    4. Restart the PC and try Settings > Windows Update > Check for updates again.
    5. Check disk and system files Because DISM without a repair source fails, first ensure the disk is healthy.
    6. Open Command Prompt as administrator.
    7. Run: chkdsk /f C: and press Enter.
    8. Approve running at next restart, then restart and let it complete.

    After that, try again:

    • DISM.exe /Online /Cleanup-image /Restorehealth

    If it still reports missing source files, configure a proper repair source as described in the next step.

    1. Configure a Windows repair source for DISM When /RestoreHealth cannot find source files, point it to a valid, fully patched repair source.
    • Ensure the repair source (for example, a mounted Windows 11 image or network share) is patched to at least the same cumulative update level as the installed OS. If the target OS is newer than the source, repairs can fail because required updated files are missing.
    • Use DISM with /Source to specify that location, as documented in DISM Operating system command-line options.

    If a central repair source is used in the environment, Group Policy can be configured under Computer Configuration > Administrative Templates > System > Specify settings for optional component installation and component repair to point Windows to that source.

    Once a valid, up‑to‑date repair source is available, rerun:

    • DISM.exe /Online /Cleanup-image /Restorehealth /Source:<your_source> /LimitAccess

    Then run Windows Update again.

    1. Temporarily remove third‑party security software Third‑party antivirus or security tools can block update installation.
    • Uninstall any non‑Microsoft antivirus/security software temporarily.
    • Restart the PC.
    • Run Windows Update again.
    • Reinstall the security software after the system is fully updated.
    1. If updates still fail, perform an in‑place upgrade If cumulative updates and DISM repair continue to fail, an in‑place upgrade using a Windows 11 ISO is a supported way to repair the OS while keeping files and apps.
    • Download the latest Windows 11 ISO from the Microsoft Software Download page for Windows 11.
    • Mount the ISO and run Setup.exe.
    • When prompted, choose to keep personal files and apps.
    • Complete the upgrade to move to the latest version (24H2 or later), then run Windows Update until no further updates are offered.

    This sequence—resetting update components, repairing disk and system files with a valid repair source, and finally using an in‑place upgrade if needed—addresses the underlying corruption that causes repeated 0x800700c1 failures and allows upgrading to newer Windows 11 versions.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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