Solved Unable to Clean Install Windows 24H2 Preview (26100.560) Using Install Media with 2 Partitions

To work around the 4GB file size limit on FAT32, I always create my Windows installation media using 2 partitions. I have a small FAT32 partition to which some of the Windows files go, but the largest part of the media, including the install.wim file are placed on a larger NTFS partition. This method has worked fine for me for years now, but it no longer works with the Windows Release Preview ISO image for 26100.560. If I instead create a single FAT32 partition on my installation media and I split my install.wim file into parts as install.swm and install2.swm, then the installation works perfectly.

Is anyone aware of a workaround that will allow me to continue using the 2 partition scheme? I suspect that this might be as easy as copying a few additional files to the first partition, but this is just speculation on my part. I'm going to see if I can figure this out, but I was curious if anyone was already aware of a solution.

Here is how I create the installation with the 2 partition scheme:

1) Create the UFD (USB Flash Drive) with a 2 GB FAT32 partition and the remaining space as NTFS. Make sure that the UFD is initialized as MBR.

2) Copy the files from my Windows ISO image to the UFD like this:

• Copy all files and folders EXCEPT the \sources folder to the FAT32 partition.

• If you are planning to use an autounattend.xml answer file, place it in the root of the FAT32 partition.

• Create a folder called sources on the FAT32 partition.

• Copy the file \sources\boot.wim to the FAT32 partition \sources folder.

• Create a folder called sources on the NTFS partition.

• Copy all files and folders from the \sources folder EXCEPT boot.wim to the \sources folder on the NTFS partition.

• If you created an ei.cfg file, copy it to the \sources folder of the NTFS partition.


Here is what happens if I boot from the installation media to install Windows:

The UFD boots fine, and the first few screens are displayed with no difficulty. After I select the disk to which Windows should be installed, the screen pops up that shows the percentage of files copied to the internal drive. However, this fails immediately while still at 0% completed. The error shown is simply "Windows 11 installation has failed".

IMPORTANT: If you boot from the Windows installation media, you will note that the initial screens look different. Apparently, this is part of a new installation experience. At the 3rd screen you will see a link that says, "Previous Version of Setup". Note that if I select that option then my dual partition UFD media will work fine. I am pursuing this because this issue also affects unattended setup and in unattended setup there is no method that I am aware of to tell it to use the "Previous version of setup". In addition, I have LOTS of batch file, programs I wrote, and other resources that create dual partition media. Not having this work is going to mean a major marathon code-writing effort

Why go through all that extra hassle? Just seems like your making life harder for yourself, what’s wrong with simply creating a bootable USB using Rufus and installing from that?

markw51 said:

Why go through all that extra hassle? Just seems like your making life harder for yourself, what’s wrong with simply creating a bootable USB using Rufus and installing from that?

Click to expand...

There is a lot that you are not aware of, and I didn't want to write a book for my question, but now that you bring it up, here is a small portion of the reasons for my doing it like this...

First, I do not use Rufus for the simple reason that I have created my own program that does a lot of what Rufus does. Remember that I ssaid I would have to rewrite code? There you go - that program is one of the things that I will need to fix.

However, you bring up a really point: I wonder if Rufus would also have a problem with this. I'm going to test it. If it does not have a problem, I'll need to see how it handles this situation.

There are other reasons as well, but I think that the above already drives home the point that I am doing this for specific reasons because I do a lot of things related to Windows setup that I can absolutely guarantee that a minimum of 99.9% of people never do

In the meantime, I have already figured out a workaround. I have more testing to do, but will post back when I have as many details worked out as I can.

More Information as a follow up to post #3 above:

I just tried Rufus. When I made a bootable thumb drive with it, it created a single partition as NTFS. I didn't see an option to do this differently, but maybe someone more familiar with Rufus can tell me if this can be avoided somehow. I saw no immediate solution.

In my case, I specifically do NOT want my installation media to be a single NTFS partition because I have some older systems that will not boot from an NTFS formatted UFD.

That alone is a good enough reason for me. The way I create the media, I can guarantee that it will work on any system, be it legacy BIOS or UEFI, and whether or not it supports booting from NTFS formatted UFDs or not.

Final post on the topic for the evening before I try to catch some snoozes.

In my post #1 above, I have bulleted the items I copy to the partitions on the UFD. Add one line like this:

• Copy the folders "boot", "efi", and "support" to the NTFS partition. Note that these three folders will now exist on both the first and second partitions. These are very small folders, so the duplication of data is very minor.

In my case, all three of the above folders amount to only 42MB, so this is my solution. If anyone discovers anything more elegant, I would love to hear it. But for now, this allows me to perform the setup with the new setup experience and more importantly, it allows unattended setups, and automated bypass of the need for a network connection and creation of a Windows account.