Hello everyone!
On this video,
I will show you how to convert disk scheme
from Master Boot Record (MBR) to a GUID Partition Table (GPT)
without losing data or reinstalling OS in windows 10 computers.
This method will allow you to switch firmware from Basic Input/Output System (BIOS)
to Unified Extensible Firmware Interface (UEFI).
IMPORTANT NOTES:
Before attempting to convert the disk to GPT:
1. Make sure that your computer supports UEFI because the conversion process can’t be reversed back without losing data.
2. Once the disk gets converted to GPT disk scheme, the BIOS firmware must be reconfigured to boot in UEFI mode.
3. Windows Recovery Environment should be enabled, so you can recover your system if you advanced into a trouble.
I will show you how to do the first 2 checks,
but if the recovery was disabled in your PC,
there is another video in description will show you how to enable it.
FIRST: How to check if your computer supports UEFI:
power on the computer and press F2 key repeatedly to open BIOS settings:
This is the list of common keys used to open BIOS settings for different brands for desktops, laptops and notebooks:
Use arrow keys from keyboards to navigate to Boot panel or read the instructions from the bottom of BIOS settings.
If there is an option to change Boot mode to UEFI or EFI, then the firmware supports the GPT disk scheme.
The boot mode settings may take another name or another path,
however, the UEFI or EFI option should be the same if its supported.
If you changed the boot mode to UEFI before conversion,
all available MBR disks will disappear,
and the computer will fail to boot with black screen error.
So don’t change it to UEFI until you convert the disk to GPT.
Now, navigate to Exit panel and select Exit Discarding Changes option...
to close BIOS menu and boot into windows.
SECOND: How to check if your disk has a GPT or MBR:
Right-click on the C partition and select Properties
Click on hardware panel and select the disk that you have windows installed on.
Click on Properties
Navigate to Volume panel then click on Populate icon
Select Volume panel again then click on Populate icon
As you can see, the partition style is MBR in my computer.
Also you can know the partition style by opening DISKPART tool then execute LIST DISK command
If there is no asterisk (*) under GPT column, the disk scheme is MBR.
If there is an asterisk, the disk scheme is GPT.
THIRD: How to convert the disk into GPT:
Type CMD into search box
Right click on Command prompt and select, Run as administrator
Execute this command to convert the disk into GPT: MBR2GPT /CONVERT /ALLOWFULLOS
If you are trying that from Windows Recovery Environment (WinRE), you have to change the CMD path to System32 folder using this command: CD /D D:\WINDOWS\SYSTEM32
Then execute the command without /ALLOWFULLOS option as following: MBR2GPT /CONVERT
If the conversion failed with this or another error message, “Disk layout validation failed for disk 0” then you have to check the followings:
1. The disk is currently having an MBR scheme
2. The Bitlocker is disabled on the disk.
3. There are no more than 3 primary partitions on the disk with at least 1-megabyte free space in all partitions
4. There is no any extended or logical partition on the disk
5. The system partition is set as active and contains valid BCD file.
In my case, the disk has an MBR scheme with enough free disk space,
the Bitlocker is disabled,
the system partition is active and contains valid BCD file, since the windows is running normally,
because the computer can’t start if the system partition is inactive or if the BCD is corrupted.
So I will check the number of partitions and whether I have logical or extended partition using DISKPART tool.
Execute LIST VOL to show available volumes
Select windows volume using this command: SEL VOL 2
Replace the 2 with the volume number of windows partitions in your computer based on its size or from the letter of windows that appears on CMD path.
Type LIST PART then press Enter to show available partitions
As you can see, there is no logical partition but there are more than 3 partitions in my disk,
so the conversions failed as seen previously.
So I will delete one partition after copying it’s contents to windows or another partition.
But the deleted partition should not be the windows partition, system partition or recovery partition.
Select the partition to be deleted using this command: SEL PART 4
Make sure to select the correct partition, because the next command will delete everything on the selected partition permanently.
Delete the selected partition using this command: DELETE PARTITION
As you can see, the partition disappeared from windows explorer,
but it’s not means I loosed the partition, because I will recreate it later.
If you are trying conversion from WinRE, you can extend the C partition using EXTEND command to include the size of deleted partition if you want,
otherwise, convert the disk and then recreate the deleted partition as you will see later.
Execute EXIT command to close the DISKPART
Press Up arrow key from keyboard to explore previous commands,
then execute MBR2GPT /CONVERT /ALLOWFULLOS again to start conversion.
As you can see, the conversion process completed successfully after removing the fourth partition,
but failed to update the Reagent.xml file with suggestion to manually disable and enable WinRE.
The following command is used to disable WinRE: REAGENTC /DISABLE
And this command is used to enable it: REAGENTC /ENABLE
However, enabling or disabling process will fail until restarting the computer.
Now power off the computer to change BIOS settings.
FOURTH: How to change settings of BIOS firmware to boot in UEFI mode:
Power on the PC then Boot into BIOS menu as seen in the first part of the video.
Navigate to Boot option and change Boot mode to UEFI.
Unlike the disk ordering in the boot list of MBR or legacy scheme,
the GPT scheme has a new boot option called Windows Boot Manager.
This option should take the first priority in the boot list in order to boot windows normally.
You may need to change the SATA Controller Mode to AHCI.
Also as we said previously,
BIOS settings and boot options are different from computer to computer...
based on firmware or hardware manufacturer.
So you have to search for boot and related options in all panels,
or search google to see how to change boot mode in your specific PC model.
Navigate to Exit panel and click on Exit Saving Changes option to boot into windows.
The first boot will take longer time, so be patient.
As you can see, the Boot or System partition is now visible and can be deleted without issues.
Also notice that the deleted partition is not visible.
To show it, right click on Start icon then select, Disk management.
Right click on Unallocated space and select, New Simple Volume option.
Change the Size of new Volume if you want,
otherwise, click next to take all available size.
Change the assigned letter if you want,
otherwise click on Next to continue.
Move the files and folders back to the new volume.
Let’s check the disk status and BCD data to confirm the conversion.
Thanks for watching.
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