Windows 10: Do I have to convert the disk from MBR to GPT in order for UEFI boot mode to work?

Hello,I am trying to solve the issue of switching from legacy to UEFI in order to be able to migrate to Windows 11. When trying to switch between them, when I choose UEFI I no longer see my disk listed in the boot sequence priority dropdown as I do for legacy. I know that switching from legacy to UEFI loses the boot sequence priority so I wanted to choose them manually but I do not have the disk listed on the dropdown menu as I did before I only see the generic descriptive Hard Disk instead of the disk's denomination.Do I have to first convert my disk from an MBR to a GPT partitioning system

:)

 

convert MBR to GPT disk

convert mbr to gpt

There is a way to convert mbr to gpt without data loss. clean command deletes all datas inside the disk, so dont use this command

boot with windows dvd , and get into command prompt

type diskpart , find the disk number , which is need to convert mbr to gpt

say disk number is 0

exit diskpart

type below command in command prompt

mbr2gpt /convert /disk:0

wait for some minutes to complete , once you get commpleted successfuly means, exit and close ,

shutdown the pc , remove windows dvd

important

After the disk has been converted to GPT partition style, the firmware must be reconfigured to boot in UEFI mode.


Make sure that your device supports UEFI before attempting to convert the disk.

 

How to convert an MBR disk into a GPT disk

Hi,

Thanks for the reply.

This is an unexpected behavior, after you convert the disk from MBR to GPT, it shouldn’t convert back automatically, however you can try to convert the disk back to GPT format if you are on Windows 10 version 1703 or later using the inbuilt utility
MBR2GPT.EXE.

• Click on Start menu (Windows logo), type
  CMD.
  
• Right click on Command prompt and select
  Run as administrator.
  
• Type MBR2GPT /validate /AllowFullOS
  
• Once the validation is successful, execute the following command and check the results.
  
• Type MBR2GPT /Convert /AllowFullOS
  
• Once the conversion is successful, you must boot the computer into BIOS and change the BIOS mode to
  UEFI.
  

Disclaimer: Modifying BIOS/ complementary metal oxide semiconductor (CMOS) settings incorrectly can cause serious problems that may prevent your computer from booting properly.
Microsoft cannot guarantee that any problems resulting from the configuring of BIOS/CMOS settings can be solved. Modifications of the settings are at your own risk.

For more information about MBR2GPT utility, please refer to the article:
Convert MBR disk into GPT using MBR2GPT.EXE

Hope it helps.

Thanks,

Peer Samie

Microsoft Community-Moderator

 

How to convert an MBR disk into a GPT disk

the asus board supports uefi 3.0 and all settings were tried already! the info you gave me converted the drive to gpt, but, it converted back to mbr after installation of clean windows! why is it doing that? it states on your site that win 10 supports
gpt and 32 bit with uefi 2.0 and above!