Windows Update Error 0xC1900101- 0x40021

Anonymous
2025-01-08T10:59:46+00:00

I've been trying to update my laptop for the past few months and I've only been getting the BSOD and this error.

I'm on the Windows 11 21H2. I've been using the Windows Updates, and even the Windows Installation assistant, I just can't seem to get past this.

Attaching the Panther and Rollback, since I usually see this being asked.

Thank you so much in advance.

Windows for home | Windows 11 | Windows update

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Ramesh 181.2K Reputation points Volunteer Moderator
2025-01-08T13:23:11+00:00

Please do a clean boot. A clean boot is the process of starting Windows without loading third-party apps and services. Please see this Microsoft article for more information.

How to perform a clean boot in Windows - Microsoft Support:

https://support.microsoft.com/en-us/topic/how-to-perform-a-clean-boot-in-windows-da2f9573-6eec-00ad-2f8a-a97a1807f3dd

(Step 3 is very important. You need to first enable "Hide all Microsoft Services" before clicking "Disable all".)

Once done, reboot Windows and try the ISO method posted by Dave.

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DaveM121 930.8K Reputation points Independent Advisor
2025-01-08T12:31:46+00:00

Hi, I am Dave, I will help you with this.

Your version of Windows 11 is 3 years out of date, you are missing versions 22H2, 23H2 and the new24H2 feature updates.

The most successful method to install version 24H2 is to use the Windows 11 ISO.

Please follow the steps, this is then not like re-installing Windows, it is just like an update and your personal files, settings and installed software will not be affected.

Click this link:

https://www.microsoft.com/software-download/win...

to download the Windows 11 ISO

When the ISO file completes downloading

Disconnect from the Internet

Disconnect all external devices with the exception of a mouse or keyboard.

Temporarily disable any 3rd party Anti-virus you may have installed

Then, in Windows File Explorer, double click the ISO and then run Setup.exe and select the Install option.

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  1. Anonymous
    2025-01-08T14:14:31+00:00

    Thanks so much!! Will let you know how it goes.

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  2. DaveM121 930.8K Reputation points Independent Advisor
    2025-01-08T13:04:41+00:00

    I do not see anything specific indicated in your logs that would indicate any driver or software that needs to be uninstalled.

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  3. Anonymous
    2025-01-08T12:58:39+00:00

    Hi Dave,

    Thanks so much for your reply. I will try this out. Although I would like to add tho that I have been trying to update my 21H2 to 22H2 and 23H2 since way, way back but I just keep on getting the BSOD and errors hence the 3years out of date version. So I’m a bit hesitant to update this if I will keep getting the same outcome.

    I was wondering if there are any apps or any softwares or drivers that I need to uninstall or update from the Panther and Rollback folders that I posted. Based on the error code that I got, it seems to be about drivers(?). I’ve checked my drivers and they seem to be up to date, not sure what else I need to do, and I can’t really understand what to do with the logs. Just wanted to take this extra step of checking the drivers or apps before I update using the ISO file.

    Thanks again!

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