Change MBR to GPT/UEFI boot without re-installation

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Categories:Windows

I got big trouble when I tried to deploy the Exadata test environment on my laptop and I found one possible solution maybe was to enable the UEFI boot mode.

When I installed Win10 on my laptop, it created a reserved partition with size 500M and I searched lots of web pages to make sure I did not need to reinstall the OS and of course without data-loss.

I already had 4 primary partitions so when I tried the command mbr2gpt I just got failed result while I knew for GPT partition type it should support much more primary partitions so what I planned to do was converting the partition type to GPT first, then removed the current reserved partition and finally created the ESP and MSR partitions.

To finished it successfully I prepared a Win10 USB installation disk and downloaded the DiskGenius free version and installed it, then run below actions as a batch:

1. Converted the MBR to GPT type

2. Removed the current reserved partition

3. Created the ESP partition first only

4. Created the MSR partition to make use of all the free space

5. Saved it to make change on the hard disk

Then I booted the laptop with the USB installation disk and entered command prompt to fix the boot issue:

1. Run diskpart to select the ESP volume and assigned mount point to it (B: here for example)

2. Located the volume having the Windows system (D: here)

3. Created below folder: B:\EFI\Microsoft\Boot\ and cd to it

3. Run command: bcdboot D:\Windows /s B: /f ALL

4. Rebooted system and select UEFI boot mode.

Done.

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