2026-09 Securityupdate (KB5124008) (26200.9445) PROBLEM

Wesley 0 Reputation points
2026-09-13T16:27:04.7933333+00:00

So my download starts fine downloadig quite slow but still, after a while it just stops and says it failed.

What can I do to resolve this? I have tried this multiple times, freed up space from the pc, rebooted etc etc..

Windows for home | Windows 11 | Windows update
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  1. Ramesh Srinivasan 87,435 Reputation points Independent Advisor
    2026-09-13T17:02:32.33+00:00

    Hi Wesley,

    To help me determine what's causing the Cumulative Update to fail, please upload your CBS logs to OneDrive and share the link here.

    The logs are available in the following folder. Copy the following folder to the desktop.

    c:\windows\logs\cbs

    Zip the folder and share the file on OneDrive or GoFile.io. Post the link here.

    Note:

    If you don't wish to troubleshoot the issue, you can do a repair installation via Settings.

    Launch Settings > System > Recovery. Under "Fix problems using Windows Update", select Reinstall now.

    (This does a repair installation, keeping your files, apps, and settings.)

    More info:

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  2. ApexNáV 265 Reputation points
    2026-09-13T16:47:59.5+00:00

    Download this update directly from the Microsoft Update Catalog using the link below, and install it manually:

    https://www.catalog.update.microsoft.com/Search.aspx?q=KB5124008

    If you are unsure which update to download, choose the one whose title exactly matches the update shown in Windows Update. Although, you can easily make sure by selecting the correct Windows version and system architecture, such as x64, 25H2 version.

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  3. AI answer

    2026-09-13T16:27:20.3933333+00:00

    Since space has already been freed and the PC has already been rebooted, the next supported steps are:

    1. Run the Windows Update troubleshooter.
      • Go to Start > Settings > System > Troubleshoot > Other troubleshooters.
      • Find Windows Update and select Run.
      • Complete the on-screen steps.
    2. Check the network connection.
      • Go to Start > Settings > Network & Internet > Wi‑Fi.
      • Verify the PC is still connected properly while the update is downloading.
    3. Clear the Windows Update cache.
      • Press Win + R, type services.msc, and press Enter.
      • Find Windows Update, right-click it, and select Stop.
      • Open C:\Windows\SoftwareDistribution.
      • Delete the files and folders inside it.
      • Return to Services, right-click Windows Update, and select Start.
      • Note: deleting the SoftwareDistribution contents resets the local update cache.
    4. Check that the Windows Update service is enabled.
      • In services.msc, open Windows Update.
      • Set Startup type to Automatic.
      • If the service is stopped, select Start, then Apply and OK.
    5. Temporarily disable third-party antivirus or firewall software.
      • Open the antivirus or firewall app from the Start menu.
      • Use its disable or pause option for a short time, then try the update again.
    6. Run Windows Update again.
      • Go to Start > Settings > Windows Update > Check for updates.
    7. If the update keeps failing, use the built-in repair option for Windows Update.
      • Go to Settings > System > Recovery.
      • In Fix problems with Windows Updates, select Reinstall now.
      • This process does not affect files, settings, or installed apps.
    AI-generated content may be incorrect. Read our transparency notes for more information.

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