Windows 10: Convert a disk from MBR to GPT in preparation for Win11 install

I ran the PC Health Check and was informed that the Secure Boot option was not enabled so I enabled it in BIOS however it was unable to find my boot drive. I figgered out that this was because my boot drive is an MBR partition style. I tried running MBR2GPT however that told me it could not find OS partition for disk 2.I tried DISKPART's, selected the disk, typed Convert GPT and was told Virtual Disk Service Error: The specified disk is not convertible.I tried the DISKPART command "filesystems" and was presented with:Type: RAWAllocation Unit Size: 512Flags: 00000000Does this mean I have to wip

:)

 

Convert only one partition on the disk from MBR to GPT

Step 2
Convert MBR to GPT without data loss

 

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.

 

Converting a MBR disk to a GPT disk

When installing Windows I was asked which drive to install it on and selected the 3TB drive, whereupon it stated it couldn't install it on there as it had a MBR and needed a GPT drive.

-> OK, with such a large disk you must use the GPT partitioning scheme.

I then tried converting it to a GPT drive using diskpart etc through the Cmd prompt with Admin privileges. But when I got to selecting the disk it told me I couldn't select it because it had a Paging
File.

-> I am not surprised.

Went online to get MS Technician to help me and he said go into the BIOS, press Ctrl-Shift-Delete keys and then Diskpart etc to convert the disk to GPT.

-> What he probably said is that you need to set the "BIOS boot mode" to UEFI.

The Windows installation process gives you the option of partitioning and formatting your disk. It probably lets you choose the partitioning scheme too, MBR or GPT. I do not know for sure since I do not
have a disk > 2 TBytes that I could test. If not then you can do this:

• Boot the machine with your installation medium.
• Select Repair Mode, then the Command Prompt.
• Use diskpart.exe to partition & format the disk.
• Install Windows.

You might ask yourself if you really want a 3 TByte System Partition. I would go for a 100 GByte System partition and a 2.9 TByte data partition.