HOW TO WINDOWS 25H2 INSTALLATION ERROR

satyam 5 Reputation points
2026-08-02T16:05:49.49+00:00

I installed the Windows Insider 26H2 build a while ago. Recently, Windows Update offered me the 25H2 update. I downloaded the update, and the installation reached 100% successfully.

However, when I restarted my computer to complete the installation, the update failed and rolled back. Windows Update now shows the following message:

Failed to install -- Error 0xC1900101

Could you please help me understand why this happened and suggest the appropriate steps to resolve the issue?

Windows Insider program | Windows Insider preview | Install, activate, and Windows update
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  1. CrazyKats 18,125 Reputation points Volunteer Moderator
    2026-08-02T16:13:40.6866667+00:00

    Hi,

    What Insider build and Channel

    are you in?

    Use WIN+R, type winver for the build #.

    A 26H2 build should not be offering

    you a 25H2 update, unless you switched

    Insider Channels.

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