W11 25H2 autounattend.xml fails, how to integrate the previous legacy setup

Labomba · Dec 23, 2025

Hi Guys,
I have been trying to use a autounattend.xml file, this created with schneegans.de
First I integrated a custom install.wim file, because I want a list of programs to be installed automatically when installing Windows to save time.
When launching the W11 25H2 setup with this custom install.wim I can only install Windows with the previous/legacy setup, if not selected I get a Windows 11 installation has failed error.

The installation can only be done while choosing the option: PREVIOUS VERSION OF SETUP in the Windows 11 setup wizard.
Now I would like to automate the W11 25H2 install with this custom install.wim and I added a autounattend.xml, but I cannot seem to find the solution to load the previous/legacy setup automatically.
In a other tread I saw that adding this the code below to the autounattend.xml should load the previous/legacy setup but all I get is a auto reboot of the installer without any errors what so ever.

Code:

<component name="Microsoft-Windows-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
    <RunSynchronous>
        <!-- Use Classic Setup -->
        <RunSynchronousCommand wcm:action="add">
            <Description>Switch to Legacy Setup</Description>
            <Order>1</Order>
            <Path>cmd /c reg add "HKLM\SYSTEM\Setup" /v CmdLine /t REG_SZ /d "X:\sources\setup.exe" /f</Path>
        </RunSynchronousCommand>
    </RunSynchronous>
</component>

Can somebody give me a clue?
Thank you in advance.

pseymour · Dec 23, 2025

This is the simplest method I’ve seen.

Problems with 24H2 autounattend install with config set

Background: Up through 23H2, I have a tried and true process for 'imaging' PCs. I understand it is antiquated, but for our small shop, it works well. Install media - USB created using the media creation toolkit WSIM used to create autounattend.xml file. AutoUnattend_Files directory in root of...

www.elevenforum.com

Some other threads:

How do I bypass the New Windows Install and only have to Old Setup?

I would like to have the old Windows Install without going through the New one at boot, How is this done? TIA John

www.elevenforum.com

W11 24h2 and old installation setup

Hello When installing W11 24h2, there is an option "Previous version of Setup" (to have the old interface) Using an autounattend file, is it possible to add this option with autounattend (or another way, registry key, etc...) ? Thanks for your help

www.elevenforum.com

hsehestedt · Dec 23, 2025

There is absolutely no reason that you should have to run legacy setup with unattended setup.

A couple of questions:

1) Are you ONLY an autounattend.xml answer file or does you custom install.wim also contain an unattend.xml?

2) Could you post a copy of your autounattend.xml here? I'd like to take a look to see if I can figure out why installation is failing for you.

Labomba · Dec 23, 2025

hsehestedt said:
There is absolutely no reason that you should have to run legacy setup with unattended setup.

A couple of questions:

1) Are you ONLY an autounattend.xml answer file or does you custom install.wim also contain an unattend.xml?

2) Could you post a copy of your autounattend.xml here? I'd like to take a look to see if I can figure out why installation is failing for you.

Hey hsehestedt,

Thnx for the reply!
I checked the Sources directory of my custom iso and it does not contain a unattend.xml, nor did I put one there.
I just found the files: unattend.dll and unattendmgr.dll
Check the content of the default autounattend.xml in attachment I used (to prevent long treads in this post), which I renamed to .txt

The part were I added the previous/legacy installer code is here below (not present in the attachment text file):
I'm not sure if I pasted the part correctly, but check what I did below please:

Code:

<settings pass="specialize">
        <component name="Microsoft-Windows-Deployment" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
            <RunSynchronous>
                <!-- Use Classic Setup -->
                <RunSynchronousCommand wcm:action="add">
                    <Description>Switch to Legacy Setup</Description>
                    <Order>1</Order>
                    <Path>cmd /c reg add "HKLM\SYSTEM\Setup" /v CmdLine /t REG_SZ /d "X:\sources\setup.exe" /f</Path>
                </RunSynchronousCommand>
                <RunSynchronousCommand wcm:action="add">
                    <Order>1</Order>
                    <Path>powershell.exe -WindowStyle "Normal" -NoProfile -Command "$xml = [xml]::new(); $xml.Load('C:\Windows\Panther\unattend.xml'); $sb = [scriptblock]::Create( $xml.unattend.Extensions.ExtractScript ); Invoke-Command -ScriptBlock $sb -ArgumentList $xml;"</Path>
                </RunSynchronousCommand>
                <RunSynchronousCommand wcm:action="add">
                    <Order>2</Order>
                    <Path>powershell.exe -WindowStyle "Normal" -ExecutionPolicy "Unrestricted" -NoProfile -File "C:\Windows\Setup\Scripts\Specialize.ps1"</Path>
                </RunSynchronousCommand>
                <RunSynchronousCommand wcm:action="add">
                    <Order>3</Order>
                    <Path>reg.exe load "HKU\DefaultUser" "C:\Users\Default\NTUSER.DAT"</Path>
                </RunSynchronousCommand>
                <RunSynchronousCommand wcm:action="add">
                    <Order>4</Order>
                    <Path>powershell.exe -WindowStyle "Normal" -ExecutionPolicy "Unrestricted" -NoProfile -File "C:\Windows\Setup\Scripts\DefaultUser.ps1"</Path>
                </RunSynchronousCommand>
                <RunSynchronousCommand wcm:action="add">
                    <Order>5</Order>
                    <Path>reg.exe unload "HKU\DefaultUser"</Path>
                </RunSynchronousCommand>
            </RunSynchronous>
        </component>
        <component name="Microsoft-Windows-Shell-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
            <TimeZone>GMT Standard Time</TimeZone>
        </component>
    </settings>

hsehestedt · Dec 23, 2025

I had forgotten how cryptic answer files generated by that web site are. I'll take a look at this later, but I have to admit that this may be difficult to unravel.

I'll let you know if I manage to find anything.

garlin · Dec 23, 2025

I was the one who first discovered this hack, but later testing demonstrated it only works where there is NOTHING else in the unattended file. If you mix it with other actions, it will break Setup.

Code:

<Path>cmd /c reg add "HKLM\SYSTEM\Setup" /v CmdLine /t REG_SZ /d "X:\sources\setup.exe" /f</Path>

If you want to force the legacy Setup client, then you should mount boot.wim and update its registry.
24H2 - Unable to install any UUP/DISM ISOs

Labomba · Jan 3, 2026

hsehestedt said:
I had forgotten how cryptic answer files generated by that web site are. I'll take a look at this later, but I have to admit that this may be difficult to unravel.

I'll let you know if I manage to find anything.

Yes, if you have another/better proposition to get the same result, please share.
And thank you for having a look!

Labomba · Jan 3, 2026

garlin said:
I was the one who first discovered this hack, but later testing demonstrated it only works where there is NOTHING else in the unattended file. If you mix it with other actions, it will break Setup.

Code:

<Path>cmd /c reg add "HKLM\SYSTEM\Setup" /v CmdLine /t REG_SZ /d "X:\sources\setup.exe" /f</Path>

If you want to force the legacy Setup client, then you should mount boot.wim and update its registry.
24H2 - Unable to install any UUP/DISM ISOs

Thank you, I will have a look!

W11 25H2 autounattend.xml fails, how to integrate the previous legacy setup

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