Unable to install Windows Security Update (KB5129195) (26200.9457)

Robin Gallardo 5 Reputation points
2026-09-16T15:04:22.49+00:00

Unable to install Windows Security Update (KB5129195) (26200.9457) with Install error Install error - 0x800f0831. I have tried several times. I am also unable to do the troubleshooter.

Windows for home | Windows 11 | Windows update
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  1. AI answer

    2026-09-16T15:04:38.0966667+00:00

    Error 0x800f0831 indicates Windows component store corruption. It can also happen when a required package is missing or not fully applied.

    Try this end-to-end path:

    1. Open Command Prompt as administrator.
    2. Run these commands in order:
    DISM /ONLINE /CLEANUP-IMAGE /SCANHEALTH
DISM /ONLINE /CLEANUP-IMAGE /CHECKHEALTH
DISM /ONLINE /CLEANUP-IMAGE /RESTOREHEALTH
Sfc /Scannow
    1. Restart the PC.
    2. Try installing the update again.

    If KB5129195 still fails, install the update manually.

    For Windows 11 24H2/25H2 ARM64, the update requires this order:

    1. windows11.0-kb5043080-arm64.msu
    2. windows11.0-kb5129195-arm64.msu

    These can be installed by double-clicking each .msu file in order, or by using DISM from an elevated Command Prompt:

    DISM /Online /Add-Package /PackagePath:c:\packages\windows11.0-kb5129195-arm64.msu

    If the required checkpoint cumulative update is already installed, Windows will indicate that it is already present.

    If the issue continues, check CBS.log at C:\windows\logs\CBS for missing package entries related to the failed update. The documented cause for 0x800f0831 is typically that the update was never installed correctly, or some packages were not applied to the registry.

    References:

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  2. Ramesh 181.8K Reputation points Volunteer Moderator
    2026-09-16T15:33:02.78+00:00

    Hi Robin,

    A repair installation should fix the issue. See Fix issues by reinstalling the current version of Windows | Microsoft Support

    Note: OTOH, if you want to fix this surgically, we need to inspect the CBS logs. 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.

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