Background
- Creating a USB bootable Windows key with Rufus results in a system that can’t startup with Secure Boot which is required for proper BitLocker activation.
- UEFI/Secure Boot USB sticks must be FAT32 not NTFS formatted.
- FAT32 volumes have a limit of 32GB. You must partition the device with a volume smaller than 32GB to proceed.
- FAT32 volumes have a file size limit of 4GB. One of the Windows installer files is over 4GB and must be split to copy to the USB stick.
Partition the USB Key
- Connect the USB key to your Windows machine or VM
- Right click on the start menu and select Disk Management
- Right click on the volume on your USB key and select Delete Volume…
- Say yes to the warning (s)
- Right click on the now Unallocated space and select New Simple Volume…
- Click Next
- Set the volume size to 16000
- Click Next
- Assign a drive letter
- Click next
- Format the drive with FAT32 and check the box for quick format (or you will be here for days). You can name it whatever you want.
Split the WIM File
- Mount the ISO for the latest version of Windows 10 (20H2 at this writing)
- Create a folder on your desktop called
wim - Open the sources folder in the root of the ISO
- Copy the
install.wimfile to yourwimdesktop folder - Open an Administrator command prompt or PowerShell session
- Navigate to the
wimfolder on your desktop - Run the command
dism /Split-Image /ImageFile:install.wim /SWMFile:install.swm /FileSize:4000
Create the USB Key
- Select all of the file and folder in the root of the ISO and copy them to the USB key FAT32 partition you created above.
- You will receive an error saying that
install.wimis too big. Click skip. - Copy the .
swmfiles that are in thewimfolder on your desktop to the sources folder on the USB key (there should be 2)