Converting BIOS/MBR Systems to UEFI/GPT Quickly with MBR2GPT

[straycat19]

Converting BIOS/MBR Systems to UEFI/GPT Quickly with MBR2GPT (ONLY FOR WINDOWS 10 1703)

 

In the UEFI newsletter I did last year, I extolled the virtues of "UEFI" firmware and its newer "GPT" disk format over the very old and  very familiar team of "BIOS" firmware and "MBR" disks.  The one problem, I noted, is that converting an already-working BIOS/MBR system to a UEFI/GPT system was possible but really hard.  Fortunately, Microsoft apparently disagrees, and included a neat new utility called "mbr2gpt" in the "Creators Edition" (yes, there should be an apostrophe there, but Microsoft doesn't use one so I'm following their lead), the new version of Windows 10 that's also called "1703."  It works best if run from the built-in WinRE, the Windows Recovery Environment.  You can get there via Settings / Update and Security / Recover / Advanced Startup / Troubleshooting / Advanced Options / Command Prompt and once you're there, you'll see in a minute that the MBR2GPT command syntax is simple.  From an elevated command prompt (WinRE command command prompts are elevated automatically), type

 

mbr2gpt /validate

 

That will check to see if mbr2gpt thinks it can safely convert your system.  If it's okay with it, just type

 

mbr2gpt /convert

 

Now, that assumes that you're booting from disk 0.  If not, add "/disk:disknumber and in any case, it'd be a really good idea to use a image backup tool like Veeam's free "endpoint" backup tool before you tried the conversion.

 

What's that you say, you're impatient and want to do this without all that diving through menus to get to WinRE? Well, you can try running MBR2GPT from a regular elevated Windows command prompt by adding the option "/AllowFullOS," although it doesn't sound like a great idea to me.  So, to repeat:

 

•This only works on Windows 10 1703 (type Winver to verify).
•Do an image backup first.
•boot to WinRE. 
•Run MBR2GPT with the /validate option. 
•If that goes well then finally /convert. 

 

Once your system drive is a GPT drive, all you need to do then is to visit your firmware settings and change your system from booting in BIOS/MBR mode to UEFI/GPT mode. As I described in the newsletter, exactly how you do that varies with your hardware, as it's the hardware vendor rather than Microsoft who lays out the firmware settings UI. And then you are totally modern!
 

Source

[jabrwky]

I used AOMEI Partition Assistant once after installing Win10 as MBR before I knew about UEFI. It converted to GPT with no data loss and booted in UEFI mode.

This is my only experience with this.

[mehdibleu]

There are multiple ways to convert MBR disk to GPT . One of them and the easiest is to use diskpart command by doing this :

 

diskpart

list disk  (note the disk number that you want to remove)

select disk X (replace X by the disk number that you noted previously)

detail disk

clean

convert gpt

exit

 

Important : Using this method implies that all data will be removed so than conversion can be effective.

 

Note : you must restart your machine so that the changes take effect

 

if you want to convert your disk from MBR to GPT without loosing data you can use this tool called Gptgen that you can download from here

once you download the tool, unzip the tool and place it into c: drive then open command prompt (in admin mode) and you will have to type this :

 

diskpart

list disk (note the disk number that you want to convert)

exit

cd C:\gptgen-1.1

gptgen.exe -w \\.\physicaldriveX (replace X by the disk number that you noted previously)

Y

 

Note : you must restart your machine so that the changes take effect

 

Important : if you wan to convert your MBR disk ( the one where your windows version is installed) to GPT to benefit of possibilities offered by UEFI, i really recommand to use the first method to remove all data to make a clean start otherwise you take the risk of having stability problems later.