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Last reply by 08-04-2022 Unsolved
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MBR2GPT error: MBR partition type of Dell OEM partition

Hi,

I am trying to use mbr2gpt to convert my windows 10 from legacy to UEFI on a Latitude E7470.

I receive the following error (both from running mbr2gpt within the OS and from an external WinPE USB drive):

ValidateLayout: Cannot map MBR partition type 222. Please supply custom mapping through the command line.

It appears that partition type 222 (hex 0xDE) corresponds to the Dell OEM recovery/utility partition that came preinstalled with my laptop. It appears the utility does not have an entry in the conversion table that gives the correct GUID for this partition type, so I have to provide one myself.

Does anyone know what the correct GUID is for this type of partition? Thank you.

Replies (18)
5 Rhenium
15800

I can't really suggest a GUID number to use because it looks like that partition type is a Dell specific and shows as a FAT 16 partition.  I certainly could be wrong but I thought Win 10 could not do FAT 16.

Could you describe the partition as to size and label?  If it was that 40 MB OEM partition, you may not need it.

_____________________________________
XPS 9365, Inspiron 7567 Gaming, Inspiron 7779, XPS One 2720, AW3423DW
System fully Win 11 compliant
2 Bronze
2 Bronze
15800

Hi Saltgrass,

The partition is labeled "OEM partition" in Disk Management and is 102 MB. I have an additional Recovery partition of about 12 GB and the main partition protected with Bitlocker.

My only worry in removing the OEM partition is that I don't know if it has any role in the boot / bitlocker process.

Thanks!

Marco

5 Rhenium
15800

If I read the info on the MBR2GPT does it say eventually you will have to redo the BitLocker setup?  If so, maybe you could do that now...

If you have a 100 MB partition, it might be a System Reserved partition which had been installed for an earlier OS, but no way for me to know.

If you want to get info on the partition to help make a decision you could use Diskpart to do that.  Open and administrative command prompt to run the commands.  One command is followed by a return and a shorthand for the commands is to use the first three letters so that partition can be par.

The overview of this process is to see what drives you have on your system.  You then select the correct drive and then the correct partition to get the details of that partition.  I will show the process to analyze the EFI system partition on my install.

:\WINDOWS\system32>diskpart

Microsoft DiskPart version 10.0.15063.0

Copyright (C) Microsoft Corporation.
On computer: TWO-IN-ONE

DISKPART> lis dis

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          953 GB  1024 KB        *

DISKPART> sel dis 0

Disk 0 is now the selected disk.

DISKPART> lis par

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
  Partition 1    System             200 MB  1024 KB
  Partition 2    Reserved            16 MB   201 MB
  Partition 3    Primary            473 GB   217 MB
  Partition 4    Primary            466 GB   474 GB
  Partition 5    Recovery           450 MB   940 GB
  Partition 6    Recovery            13 GB   940 GB

DISKPART> sel par 1

Partition 1 is now the selected partition.

DISKPART> det par

Partition 1
Type    : c12a7328-f81f-11d2-ba4b-00a0c93ec93b
Hidden  : Yes
Required: No
Attrib  : 0X8000000000000000
Offset in Bytes: 1048576

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
* Volume 2         ESP          FAT32  Partition    200 MB  Healthy    System

DISKPART>

_____________________________________
XPS 9365, Inspiron 7567 Gaming, Inspiron 7779, XPS One 2720, AW3423DW
System fully Win 11 compliant
2 Bronze
2 Bronze
15800

No need to redo the Bitlocker setup with mbr2gpt, it is sufficient to temporarily remove the protectors.

Following the steps you detailed for the OEM partition I only get

Partition 1

Type  : DE

Hidden: Yes

Active: No

Offset in Bytes: 32256

which unfortunately does not seem to provide more details than what we knew already. As far as I understand, this is the partition used for Dell diagnostics tool, but I cannot be 100% sure. I wish there was a way to temporarily disable it in the boot sequence to make sure it does not play a critical role.

By the way, I have asked the same question in the comment section of the official documentation article on mbr2gpt, if I learn something there I will update it here too.

Thank you for your help.

5 Rhenium
15805

You did not get any of the info regarding the listing of formatting type or size?

At one time, there was a situation with a Partition manager which would turn recovery partitions into OEM partitions.  At that time, I believed it only happened with UEFI installs.  Since the Partition type you are seeing is specific to Dell, this situation is probably not in play, but have you ever used EaseUS to configure the partitions on your system?

If you wanted to attach a picture of your Disk Management window, it might help someone see something familiar.  You can do that by using the Rich formatting.  I normally limit the picture size to 250-300 wide.

Have you given any thought to doing a clean install?

_____________________________________
XPS 9365, Inspiron 7567 Gaming, Inspiron 7779, XPS One 2720, AW3423DW
System fully Win 11 compliant
2 Bronze
2 Bronze
15805

Thanks a lot for following up. Compared to factory settings, I have only migrated to a larger disk using clonezilla and enlarged the OS partition. I have also upgraded from Win7 to Win10.

I am attaching a screenshot of my Disk Management window.

Yes, I think a clean install is becoming more and more attractive compared to this.

5 Rhenium
15881

It looks like you have altered the original configuration which makes it hard to know for sure what you should do.

I know you are booting from the 11 GB partition because it is marked as Active.  So your boot files and probably the BitLocker info is there, but again, I am not familiar with BitLocker operations.  A partition that large normally contains the Recovery image for the original OS.

The 100 MB partition appears to have been the original System Reserved partition, which was an NTFS partition using the normal partition type.  At one time, it contained the Boot files and Recovery tools but now appears to not be used...

Because you cloned from a prior drive, the partition sizes may have been changed or otherwise modified.  So I cannot suggest anything and be certain it would not cause problems for your system.

I don't know how old your system is but since it appears to be UEFI capable, a clean install will, in many cases, improve performance.  

_____________________________________
XPS 9365, Inspiron 7567 Gaming, Inspiron 7779, XPS One 2720, AW3423DW
System fully Win 11 compliant
2 Bronze
2 Bronze
15881

I had the same issue on a Dell E7270. I used the example given and it worked flawlessly for me. For example...

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

2 Bronze
2 Bronze
12553

Hi

Same issue on Dell 3020;

Syntax only worked without the brackets....

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

When you follow the Microsoft Mechanic Article to see the new GPT disk in diskpart as in https://docs.microsoft.com/en-us/windows/deployment/mbr-to-gpt#logs the disk o is not showing. This can be disconcerting as it says successful then disappears. If the PC is restarted, the same issue comes back and if shutdown, it restarts.

Solution is to restart and hit F12 key and get a one time boot window then to change settings ti UEFI ... all works then.

Peter

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