MBR2GPT is failing to convert the System Disk (error 0x00012, Cannot map MBR partition type 23)

2020-01-06

Question

_{Monday, January 6, 2020 9:20 AM}

Log files: https://mega.nz/#!zhhSkAIJ!VD9sjLdhPAecIB0EO6zIEgV1ODw1pB4aWzDgAAdbdoo![]()

As you can see from the error it won't let me convert the Disk. I've been following information here https://docs.microsoft.com/en-us/windows/deployment/mbr-to-gpt and used the mbr2gpt /allowFullOS /validate command which says everything is valid for conversion and then the mbr2gpt /allowFullOS /convert /logs:c:\mbr2gpt which fails. I'm not fully grasping what the issue is though, like what should I be doing?

Thank you, I recently changed motherboards & CPU to a UEFI enabled system and would like to get Windows to fully utilize UEFI specific features for optimal performance/compatibility.

All replies (7)

_{Tuesday, January 7, 2020 3:24 AM}

Hi,

This is happening because you have more than 3 partitions on your disk 0 or disk 1 where you have the windows 10 installed. Or probably you have selected wrong disk. try on disk 0.

You could try the command below:

mbr2gpt.exe /convert /disk:0 /map:222=af9b60a0-1431-4f62-bc68-3311714a69ad /allowFullOS

When you follow the article to see the new GPT disk in diskpart as in /en-us/windows/deployment/mbr-to-gpt#logs the disk o is not showing. This can be disconcerting as it says successful then disappears.

Solution is to restart and hit F12 key and get a onetime boot window then to change settings in UEFI.

In addition, here are some posts with the similar issue with yours, just for your reference, you can try the method mentioned in them:

https://techcommunity.microsoft.com/t5/windows-10/shifting-from-bios-to-uefi-with-the-windows-10-creators-update/m-p/60064

Hope above information can help you.

Please remember to mark the replies as answers if they help.
If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

_{Tuesday, January 7, 2020 5:39 AM}

but... there are only 3 partitions? I performed a Migrate OS to SSD/HD Wizard via the Minitool Partition Wizard when I got this SSD, to copy my O/S to the SSD.

_{Wednesday, January 8, 2020 9:32 AM}

Hi,

Have you tried the command?

Did it work or not?

Please remember to mark the replies as answers if they help.
If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

_{Wednesday, January 8, 2020 3:16 PM}

Nah it didn't, so I went the long method of moving all the important stuff to another drive and deleting all the partitions on the disk in order to convert it to GPT and then installing Windows to it.

_{Thursday, January 9, 2020 7:09 AM}

Hi,

Sorry for the inconvenience.

In addition, thanks for sharing your efforts in the forum as it would be helpful to anyone who encounters similar issues.

If there is anything else we can do for you, please feel free to post in the forum.

Best Regards,

Farena

Please remember to mark the replies as answers if they help.
If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

_{Thursday, January 9, 2020 6:15 PM}

Yeah all the alternatives I could find involved paid versions of products (the feature is locked out of free/trial versions) and there was no guarantee they'd fair any better than MBR2GPT so I didn't bother with trying any of them.

_{Monday, January 13, 2020 7:16 AM}

Hi,

You're right.

I learn more from your reply, and I believe partners who may visit this thread in the future will benefit from your sharing.

Please remember to mark the replies as answers if they help.
If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

Share via

MBR2GPT is failing to convert the System Disk (error 0x00012, Cannot map MBR partition type 23)

Question

All replies (7)

Additional resources