Cannot select system partition

[sonicserve]

I want to boot both BIOS-based and UEFI-based computers. So on my USB hard drive I created a System FAT partition(350M) and a NTFS boot partition. But it does not allow me to select the system partition. There is no radio button for the system partition. What is the problem?

I am using WinToUSB Free v3.1. I am trying to install Windows 10 Pro 64 bits. My USB hard drive is using MBR partition.

Screenshot is attached.

[sonicserve]

I finally figured out why. The system partition must be FAT32. I made a mistake and used FAT. It is working now WinToUSB is really a nice tool. Thank you

[admin]

I finally figured out why. The system partition must be FAT32. I made a mistake and used FAT. It is working now WinToUSB is really a nice tool. Thank you

Yes, you are right, WinToUSB requires that the EFI system partition (ESP) should be FAT32.