Bootable Windows install USB devices UEFI

Hi there
there's definitely a problem on some older computers with UEFI boot if the iso file is > than 4.5 GB. Up to that the file system is FAT32 and computers will boot OK. If greater than that then NTFS appears to be forced and some computers won't boot .

I think the absolute limit is in fact the current Windows iso created by the mct which has a size of 4.463,295 KB which boots OK.

If the iso is any bigger I think somewhow you need to split the install.wim and mess around with it that way.

Shouldn't be a problem on modern machines but we aren't always running the latest hardware.

Running as a VM and restoring back to a physical machine using Macrium and attempting to fix the boot problems won't work either in some machines as the bootloader will be the new NTFS/EFI one which will fail probably with message "Inacessible boot device" or something similar. As a VM the bootloader is different of course !!! so the VM will boot regardless.

So if you can't install or keep getting boot failures this could be the cause.

Cheers
jimbo

Latest versions of Windows 10 ISO contains WIM file that is big for FAT32 file system.

Files larger than 4GB can NOT be stored on a FAT32 partition. This is due to FAT32 limitation.

If you want to boot under UEFI firmware by utilizing NTFS file system you might fail, as not all UEFI systems are able to boot from external boot media using NTFS.

This tutorial will show you how to extract the needed edition from the original install.wim to get a smaller install.wim file.


1 Extract the required install.wim out of the ISO file or mount the ISO file.

2 Open the Command Prompt by typing cmd.exe into Start Menu, right-click on Cmd.exe, and open it as an administrator.

3 Execute the following DISM command with the correct path to the install.wim to get the index that represents needed Windows edition:

Code:

Dism /Get-WimInfo /WimFile:"E:\Sources\install.wim"

The output might look like the following:


4 Execute following command to create a "Mount" folder at root of C: partition.

Code:

Md C:\Mount

5 Extract the right index (6 in this case as I want to install Windows 10 Pro edition) into a new WIM file via DISM command:

Code:

Dism /Export-Image /SourceImageFile:"E:\sources\install.wim" /SourceIndex:6 /DestinationImageFile:"c:\Mount\install.wim

Replace the "E:\sources\install.wim" path with correct path to the install.wim file.

It reduced the install.wim file size to only 3.80 GB which will now fits within the file size limitation of FAT32.

6. Copy newly created install.wim file stored within C:\Mount folder onto an already prepared USB stick with all the other needed files from the original ISO.

FreeBooter said:

Latest versions of Windows 10 ISO contains WIM file that is big for FAT32 file system.

Files larger than 4GB can NOT be stored on a FAT32 partition. This is due to FAT32 limitation.

If you want to boot under UEFI firmware by utilizing NTFS file system you might fail, as not all UEFI systems are able to boot from external boot media using NTFS.

This tutorial will show you how to extract the needed edition from the original install.wim to get a smaller install.wim file.


1 Extract the required install.wim out of the ISO file or mount the ISO file.

2 Open the Command Prompt by typing cmd.exe into Start Menu, right-click on Cmd.exe, and open it as an administrator.

3 Execute the following DISM command with the correct path to the install.wim to get the index that represents needed Windows edition:

Code:

Dism /Get-WimInfo /WimFile:"E:\Sources\install.wim"

The output might look like the following:


4 Execute following command to create a "Mount" folder at root of C: partition.

Code:

Md C:\Mount

5 Extract the right index (6 in this case as I want to install Windows 10 Pro edition) into a new WIM file via DISM command:

Code:

Dism /Export-Image /SourceImageFile:"E:\sources\install.wim" /SourceIndex:6 /DestinationImageFile:"c:\Mount\install.wim

Replace the "E:\sources\install.wim" path with correct path to the install.wim file.

It reduced the install.wim file size to only 3.80 GB which will now fits within the file size limitation of FAT32.

6. Copy newly created install.wim file stored within C:\Mount folder onto an already prepared USB stick with all the other needed files from the original ISO.

Thanks - much appreciated


Cheers
jimbo

You are very welcome!

Hi there
Current recommended iso made with the MCT won't boot on an older machine I have with AMD processor. Early version of 1909 is about the latest version of Windows that boots on that machine.

I have an even OLDER machine with INTEL processor and BIOS/MBR - that works !!!!!

The AMD machine is an HP Proliant GEN 10 Microserver with Opteron 4321 processor and Radeon graphics with 16 GB RAM.
No reason I can think of why this machine steadfastly won't install the currently recommended version of W10.

Nothing newer than this will boot or even install



Cheers
jimbo

It is set to 3500mb , you can change it here

Try3 said:

Freebooter,

The problem with that method is that a 21H1 ISO's install.wim is still too big for FAT32 even when a single Edition is extracted. I used to use this method but could not this time. My post
Create Edition-specific Fat32 InstallUSB - [my post #555] - TenForumsTutorials
is not valid for 21H1 install.wim.

Unless the MCT is used to download the install.esd variant instead, the other solution is to split the install.wim into FAT32-sized chunks. See
Windows 10 ISO contains WIM file that is big for FAT32 file system - Dell US

Denis

Hi there

thanks for the idea - others have also suggested that BUT :

it's actually an esd file (there's no install.wim in the iso made by the MCT) and size is about 3.9 GB so that in this case isn't the problem.





I guess this machine will just have to run Windows as VM's.

Cheers
jimbo

Current recommended iso made with the MCT won't boot on an older machine I have with AMD processor. Early version of 1909 is about the latest version of Windows that boots on that machine.

Did you try making the iso yourself ?

And/or did you try replacing the contents of the successful 1909 iso with newer files?