How to Convert Windows 10 MBR to GPT so you can boot on a new UEFI system vs. older Legacy BIOS boot

You've been Googling this and it's much simpler than it seems. This is not a 100% walkthru but there was ONE THING that made it so the disk wouldn't validate as being able to be converted:

You have to shrink your partition a little. I don't know why, but that's all I did.

WARNING: This can result in data loss, but my install wasn't that important so I didn't back up. You've been advised. :)

Other things:

Don't do the conversion in Windows. Boot to the recovery mode (also called WinPE or other stuff) to use mbr2gpt.exe

Make sure Windows 10 is updated. The validation on older than 1709 versions of Windows fail.

1. Shrink your system partition by 1GB. Can be done in 

2. Boot into Recovery Mode and re-validate the disk. Then convert it using mbr2gpt.

I got an error about WinReReapir (that's how it was spelled...looks like a typo) and 'failed to update reAgent.xml but Windows 10 booted fine after the conversion.

My scenario was: 2.5" SSD in older Legacy BIOS system only. Wanted to put it in Dell G5000 which is UEFI only.

Booted fine first try.

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