Disabling CSM doesn't allow boot to Windows

Supra said:

That's not my problem.

The rest of us know that including myself.

For those who didn't read the OP's initial post, his issue is he wants to use Secure Boot, which requires a UEFI platform, which in turn requires GPT disks?

Given that, I see no reason to convert all disks to GPT, just the boot drives, but...

sygnus21 said:

For those who didn't read the OP's initial post, his issue is he wants to use Secure Boot, which requires a UEFI platform, which in turn requires GPT disks?

Given that, I see no reason to convert all disks to GPT, just the boot drives, but...

UEFI does NOT require a GPT disk!!!

NavyLCDR said:

UEFI does NOT require a GPT disk!!!

IT WAS A QUETION THUS THE QUESTION MARK!!!!!

Thank you!

I like to use MiniTool Partition Wizard Free:
Best Free Partition Manager for Windows | MiniTool Partition Wizard Free

Normally Windows won't let you mess with the system partition the computer boots from, but MiniTool Partition Wizard will. You can attempt to just convert the NTFS system partition to FAT32 with it. Then assign a drive letter to it, let's say T:. Then the bcdboot command would be:
bcdboot C:\Windows /s T: /f ALL

That would make it bootable in both CSM and UEFI modes. Or you might have to delete the partition, create a new FAT32 partition, mark it as active, then use the bcdboot command. I would highly recommend having an image backup before you mess with the system partition if you don't know how to create it from scratch using a bootable USB rescue flash drive.

The requirements for booting basically are:
Legacy BIOS or CSM mode:
MBR drive
FAT32 or NTFS primary partition marked as active (can be the Windows partition)
BIOS compatible BCD

UEFI:
MBR or GPT drive
FAT32 partition (therefore must be separate from the Windows partition)
UEFI compatible BCD

Therefore, an MBR drive with a FAT32 primary marked as active with a BCD containing files compatible with both BIOS and UEFI booting will boot in either mode.

NavyLCDR said:

I would highly recommend having an image backup before you mess with the system partition if you don't know how to create it from scratch using a bootable USB rescue flash drive.

Would you recommend Macrium Reflect to do this, or can Windows do it? (I normally have system protection turned off)

Macrium Reflect.

NavyLCDR said:

I like to use MiniTool Partition Wizard Free

So I can't use this without buying it; converting to FAT32 is a 'Pro' feature that even the Demo won't allow me to do. Would EaseUS or AOMEI do the job?