I’ve tried to install Windows 10, so I have downloaded the ISO from MSDN, and used the Windows USB/DVD Download Tool to write it to a pendrive. However, my computer refused to recognize the installation media, so I didn’t have to option to boot from it. In my BIOS the boot options were set to UEFI boot ON, secure boot ON, which worked well for the previous Windows 8.1, but now these settings caused the problem. If I changed that setting to Legacy boot ON, secure boot OFF, the boot from USB option appeared, and the Windows installer successfully started. Unfortunately this is not the happy end of the story, because the installer later stopped with this error:
Windows cannot be installed to this disk. The selected disk is of the GPT partition style.
After some googling I’ve found several methods to convert a GPT partition to MBR (with loosing all data on the whole disk, or by using a 3rd party boot CD), but fortunately there is a much easier method.
The much easier method
The real issue is that UEFI boot does not work with NTFS pendrives (at least not in my machine), so the solution is to
use a FAT32 pendrive.
Unfortunately the Windows 7 USB/DVD Download Tool always reformats the pendrive to NTFS, even if it was formatted previously, so you need another tool to prepare the installer pendrive.
You can use diskpart for example, which is a built-in command line tool in Windows.
Let’s start it:
Get a list of the available drives:
You will see the pendrive in the list (because hopefully you previously inserted it), you can recognize it from its size. Tell the tool that you want to work with that disk:
select disk 2 (use the correct number instead of 2)
Remove every content from the disk (you will lose your existing data on the pendrive!):
Create a new FAT32 partition:
create partition primary select partition 1 active format quick fs=fat32 assign
Now you can quit from diskpart:
The last step is to copy the installer to the pendrive. First, mount to ISO, and copy its content to the disk, for example with xcopy (in this example D: is the mounted ISO drive, F: is the target pendrive):
xcopy d:\* f:\ /s /e
With that your BIOS will hopefully recognize the pendrive, so you will be able to boot from it, and you will not have any problem with the GPT partition, even if UEFI and secure boot is turned on.