Convert Windows 10 Boot Drive Partitions from MBR to UEFI

I would like to convert a boot drive partition that has 2 windows 10's installed on them from MBR to UEFI. Is this possible to do without loosing data and reinstalling windows.

NIK1 said:

I would like to convert a boot drive partition that has 2 windows 10's installed on them from MBR to UEFI. Is this possible to do without loosing data and reinstalling windows.

Yes. You will have to backup the Windows 10 partitions to another drive. Then convert the system drive to GPT, then restore the Windows 10 partitions back to the system drive.

Thanks for the info..If I back them up with say Macrium Reflect and then convert the drive partitions to UEFI,go in bios and change from MBR to GPT, then restore with MR, will that work and will they boot.

NIK1 said:

Thanks for the info..If I back them up say with Macrium Reflect and then convert the drive partitions to UEFI,go to bios and change from mbr to uefi then restore with MR will that work and will they boot.

Not automatically- and you are confusing a bunch of terms. What you need to do, if you want to convert the drive to GPT and boot in UEFI mode is:
1. Using Macrium Reflect Free, back up your Windows partitions. I am assuming you don't have any data partitions, but if you do have any partitions dedicated to data you need to back them up too.
2. Erase the installed hard drive and convert it to GPT. This is done with the diskpart command "clean", followed by "convert GPT".
3. Create a new 100mb FAT32 partition to be used for the EFI system partition. This is done with the diskpart command "create partition EFI size=100". Then you should give it a drive letter such as T:, diskpart "assign letter=T".
4. Then restore your two Windows partitions (and any data partitions). Let's say the get drive letter C: and D:
5. Then you will need to write boot files to the newly created EFI system partition using BCDBOOT commands:
bcdboot C:\Windows /s T: /f UEFI
bcdboot D:\Windows /s T: /f UEFI /addlast /d
6. Then change your UEFI (BIOS) settings to boot in UEFI mode.

Brink said:

Hello NIK1,

You could use the method in the tutorial below to convert from Legacy BIOS (MBR) to UEFI without data loss.

Convert Windows 10 from Legacy BIOS to UEFI without Data Loss

I don't think mbr2gpt works on dual boot systems where there are 2 OS partitions on the same drive. Quoted from the tutorial, "If you dual boot Windows 10 with any other operating system, then do not use this tutorial. This tutorial is only meant for a standalone Windows 10 installation on a PC."

I think AOEMI Partition Manager lets you do that. The paid version, of course...