Shifting from BIOS to UEFI with the Windows 10 Creators Update MBR2GPT disk conversion tool

[Zachary Cavanell]

Comprehensive yet quick video overview that explains how you can safely and non-destructively convert a Windows 10 machine from legacy BIOS to UEFI disk partitioning; and how you can automate the conversion as part of your in-place upgrade process from Windows 7 to Windows 10.

[#2]

One thing I noticed when performing the conversion during an upgrade task sequence, you will lose the ability to "rollback" to previous build of Windows 10. This makes sense but I didn't see it documented anywhere.

[#3]

is it necessary to have Creators update to execute mbr2gpt command?

[#4]

It's necessary to have Creators Update if you wish to run the tool from within Windows (Full OS). MBR2GPT does support older versions of Windows 10 when ran from the WinPE thats included in Windows ADK 1703.

[#5]

I get this error when trying to do the /validate
ValidateLayout: Wrong boot partition count, expected 1 but found 0.

Any idea why that is?

[#6]

Just from the look of the error, it sounds like it cannot find a boot partition. How are you running the command?

[#7]

mbr2gpt /disk:1 /validate

I have tried from both WinPe and within Windows.

This is the full transcript for the command prompt.

C:\Windows\system32>mbr2gpt /disk:1 /validate /allowfullos /logs:c:\temp
MBR2GPT: Attempting to validate disk 1
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 1

[#8]

Is there a reason your validating against disk 1? Try this:
mbr2gpt /disk:0 /validate

[#9]

My OS is intalled on Disk 1
So if I run is on disk:0 then I get this error instead.

C:\Windows\system32>mbr2gpt /allowfullos /validate /disk:0
MBR2GPT: Attempting to validate disk 0
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Cannot find OS partition(s) for disk 0

[#10]

hi 

i tried to convert from mbr to gpt using the cmd 

my widows builed is 1703 

when i enterd the command to validate the disk 

this is the message that i got

can you please help me to know what is wrong

my laptop allow for uefi

C:\Windows\system32>mbr2gpt /validate /disk:0 /allowfullos
MBR2GPT: Attempting to validate disk 0
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 0

thanks in advanced

[#11]

Error while validating Disk

C:\WINDOWS\system32>mbr2gpt /allowFullOS /validate
MBR2GPT: Attempting to validate disk 0
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 0

[#12]

Hello, I also get this error: Cannot find OS partition(s) for disk 0.

The OS is installed on Disk0. Did you find a fix?

[#13]

I did not :(

[#14]

hi, if mbr disk have 4 partitions it will fail, i deleted one partition then it worked.

[#15]

Does this work for Home or Pro versions of Windows 10? Or just enterprise?

[#16]

Pro working, so home must work too.

[#17]

Check your setupact.log & setuperr.log files in %Windir%\Panther. There should be some verbose information in one of those logs.

-Mike

[#18]

found any solution?
same error here stuck with it

[#19]

Trying OS is intalled on Disk 0
only have 3 drives left remove one already 

now C: OS, D:Data , F: System Reserved
 Still getting this error

please help

C:\Windows\system32>mbr2gpt /allowfullos /validate /disk:0

MBR2GPT: Attempting to validate disk 0

MBR2GPT: Retrieving layout of disk

MBR2GPT: Validating layout, disk sector size is: 512 bytes Cannot find OS partition(s) for disk 0 

[#20]

Trying OS is intalled on Disk 0
only have 3 drives left remove one already 

now C: OS, D:Data , F: System Reserved
 Still getting this error

please help

C:\Windows\system32>mbr2gpt /allowfullos /validate /disk:0

MBR2GPT: Attempting to validate disk 0

MBR2GPT: Retrieving layout of disk

MBR2GPT: Validating layout, disk sector size is: 512 bytes Cannot find OS partition(s) for disk 0 

[#21]

I accidentally deleted the MSR partition from the drive when downloading Windows. Should I recreate the MSR? If so, does anyone know how to do it?

[#22]

Tried a lot. 

I am getting an "unrecognized partition error".

This is my partition setup.

I have attached the log files below.

Somebody please help :(

[#23]

There is a partition on the disk MBR2GPT doesn't like. Try running the following diskpart commands:

DISKPART> select disk 0

DISKPART> list partition

.

.

.

DISKPART> select partition 1

DISKPART> detail partition

.

.

.

(repeat for each partition)

You should be able to see which one is causing issues.

[#24]

Mike, I hope you will spend a few minuttes looking over this, as I can't figure it out on my own.

Is the attached information sufficient?

Thanks in advance.

Diskpart overviewMBR2GPT validation and result

[#25]

Error 0x0000057 means: The disk structure is corrupted and unreadable.

Try running chkdsk and see if it finds anything wrong with the disk.

[#26]

No luck. ChkDsk reported no errors.
Still error 0x571

Btw. I never saw 0x57 - only 0x571

[#27]

Sorry - typo on my part. 0x571 is what I meant to type. What make/model is the system and how was it built? If I had to guess, it is having an issue with the third partition. Type 39 is Bell Labs partition type.

[#28]

I understand that the MBR2GRT.exe will support versions of Win 10 previous to 1703 and should work when booted from a Win PE 1703 disk.

So I downloaded & install Windows ADK 1703 & made a Win PE disk. I booted from that disk and ran MBR2GPT /validate and the result was "unable to validate disk." Any ideas? It's a 500gb disk with about 90gb free. Is free space the problem?

Larry Hess CAP | Albuquerque, NM | www.LarryHesscpa.com

[#29]

Hi Mike,

It's a Dell Latitude E7450.
However, I think I've located the problem.

I created a new WinPE image, and now it works. The same system is converted, and BIOS settings changed, and now all is fine.

The new WinPE image is 10.0.15063 where the old one was 10.0.10240

Can you verify that mbr2gpt.exe will only run on WinPE images based on boot.wim from a 1703 media?

[#30]

Yes - it requires WinPE from the ADK 1703 (there are other files that are necessary for it to run correctly). Plus, it is only supported to run on either WinPE 1703, Windows 10 1703 or later.

[#31]

This makes sense as the conversion process will create one partition hence you at most can have three existing partitions. The documentation here:

https://docs.microsoft.com/en-us/windows/deployment/mbr-to-gpt

actually states:

There are at most 3 primary partitions in the MBR partition table

But, again a shoutout to Microsoft developers: The errors you (Developers) throw are not there for so only you can debug your code. They are first and foremost for the user to understand what has gone wrong. So the question remains: Why is there no error message on validation that states: There are too many partition on disk x, please reduce the number of partitions to at most 3 to be able to convert. --> This should not be that hard.

[#32]

Hi,I can't convert it from MBR to GPT.

This is the error:

MBR2GPT: Attempting to validate disk 0
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 0

[#33]

Thank you for your information. It's very helpfull.

[#34]

MBR works with disks up to 2 TB in size, but it can’t handle disks with more than 2 TB of space. MBR also only supports up to four primary partitions — if you want more, you have to make one of your primary partitions an “extended partition” and create logical partitions inside it. This is a silly little hack and shouldn’t be necessary.
GPT stands for GUID Partition Table. It’s a new standard that’s gradually replacing MBR. It’s associated with UEFI — UEFI replaces the clunky old BIOS with something more modern, and GPT replaces the clunky old MBR partitioning system with something more modern. It’s called GUID Partition Table because every partition on your drive has a “globally unique identifier,” or GUID — a random string so long that every GPT partition on earth likely has its own unique identifier.

This system doesn’t have MBR’s limits. Drives can be much, much larger and size limits will depend on the operating system and its file systems. GPT allows for a nearly unlimited amount of partitions, and the limit here will be your operating system — Windows allows up to 128 partitions on a GPT drive, and you don’t have to create an extended partition.

On an MBR disk, the partitioning and boot data is stored in one place. If this data is overwritten or corrupted, you’re in trouble. In contrast, GPT stores multiple copies of this data across the disk, so it’s much more robust and can recover if the data is corrupted. GPT also stores cyclic redundancy check (CRC) values to check that its data is intact — if the data is corrupted, GPT can notice the problem and attempt to recover the damaged data from another location on the disk. MBR had no way of knowing if its data was corrupted — you’d only see there was a problem when the boot process failed or your drive’s partitions vanished.

[#35]

For the people who are getting the following error when validating:

Cannot find OS partition(s) for disk X

First make sure you have the correct disk selected with the Windows installation.

If this is the case there is probably something wrong in your BCD configuration. If you have a simple single boot system, you can easily rebuild it from a elevated prompt with:

bcdboot.exe X:\Windows

After that it should validate just fine (it did in my case).

X is dependent on your system. In most cases 0 and C

[#36]

Cannot find OS partition(s) for disk X

First make sure you have the correct disk selected with the Windows installation.

If this is the case there is probably something wrong in your BCD configuration. If you have a simple single boot system, you can easily rebuild it from a elevated prompt with:

bcdboot.exe X:\Windows

After that it should validate just fine (it did in my case).

X is dependent on your system. In most cases 0 and C

[#37]

Just done this on one of our work machines. If this works it'll save us bloody hours so cheers MS. One question though it seems to have gotten to "Fixing drive letter mapping" and stopped. Checking everything else it seems fine, disk converted , lovely... so is it safe to restart and change the BIOS/UEFI options or does this take a dam sight longer than the video hinted at?
Up to 40 minutes now.

[#38]

I had some error..  I tried this mbr2gpt /validate /disk:1 /allowFullOS /logs:c:\temp\Errors 

  Error make sense, Msg="ValidateLayout: Too many MBR partitions found, no room to create EFI system partition." 

  4 primary and no extended is valid for MBR, but tool probably need space to create 1 new partition before conversion.

  other problem was not existence of Recovery partition - i just copied it from Windows 7 Efi instalation, is mostly just empty space - to backup image is few MB big.

[#39]

This tool is very beta, poor coding, new error:

cannot rely on this space

<z:row Cls="D" Sev="50331648" Maj="Def" Min="Def" LN="4099" Fil="" Fun="pExecuteConversion" Uid="50331648" Msg="MBR2GPT: Partition final size is: 248640438272 (initial size was 248640438272), cannot rely on this space" PID="14424" TID="14612" Con="" Exe="C:\WINDOWS\system32\MBR2GPT.EXE" Mod="MBR2GPT.EXE" Err="0" MD="" DT="2018-04-10T20:48:51"/>

 Validation is succeffull.

[#40]

I Just resolved the validation issue. 

basically you must not have more than three partitions and not any free space left on the hard drive.
if you check the list of partition on DISKPART you will see that even the free space is listed as a partition.
you can use tools like disk manager (built-in windows) or minitool to resize the current partitions to take up the left over free space then validate mbr2gpt again. 

hopefully it works for you too :) 

let me know

[#41]

Here is what my HD looks like using DISKPART:

DISKPART> list volume

Volume ### Ltr Label Fs Type Size Status Info
---------- --- ----------- ----- ---------- ------- --------- --------
Volume 0 E DVD-ROM 0 B No Media
Volume 1 C 790 SSD NTFS Partition 449 GB Healthy System
Volume 2 D Recovery NTFS Partition 15 GB Healthy
Volume 3 RAW Partition 856 MB Healthy Hidden
Volume 4 RAW Partition 455 MB Healthy Hidden

And the attached PDF shows what it looks like using the Disk Management extension of the Computer Management console.

How would you suggest dealing with these partitions in order to be able to sucessfully run MRS2GPT?

[#42]

Here is what my HD looks like using DISKPART:

DISKPART> list volume

Volume ### Ltr Label Fs Type Size Status Info
---------- --- ----------- ----- ---------- ------- --------- --------
Volume 0 E DVD-ROM 0 B No Media
Volume 1 C 790 SSD NTFS Partition 449 GB Healthy System
Volume 2 D Recovery NTFS Partition 15 GB Healthy
Volume 3 RAW Partition 856 MB Healthy Hidden
Volume 4 RAW Partition 455 MB Healthy Hidden

And the attached PDF shows what it looks like using the Disk Management extension of the Computer Management console.

How would you suggest dealing with these partitions in order to be able to sucessfully run MRS2GPT?

[#43]

Thank you! This was exactly what I needed to do.

[#44]

I have been trying to use this converter for a few days now and always get stuck on 

MBR2GPT: Trying to shrink the OS partition

Here is the log:

2018-08-01 12:16:43, Info MBR2GPT was explicitly asked to run in full OS mode.
2018-08-01 12:16:43, Info MBR2GPT: Attempting to convert disk 0
2018-08-01 12:16:43, Info MBR2GPT: Retrieving layout of disk
2018-08-01 12:16:43, Info MBR2GPT: Initial partition information
2018-08-01 12:16:43, Info ===========================================================
2018-08-01 12:16:43, Info Partition layout for disk: 0
2018-08-01 12:16:43, Info Partition style : MBR
2018-08-01 12:16:43, Info MBR signature: 3030528643
2018-08-01 12:16:43, Info Number of partitions : 1
2018-08-01 12:16:43, Info ===================PARTITION===============================
2018-08-01 12:16:43, Info Number: 1
2018-08-01 12:16:43, Info Type: 7
2018-08-01 12:16:43, Info Boot: Yes
2018-08-01 12:16:43, Info Recognized: Yes
2018-08-01 12:16:43, Info Style: 0
2018-08-01 12:16:43, Info Offset: 1048576
2018-08-01 12:16:43, Info Length: 958046142464
2018-08-01 12:16:43, Info Volume: \\?\Volume{b4a23283-0000-0000-0000-100000000000}\
2018-08-01 12:16:43, Info Drive: C:\
2018-08-01 12:16:43, Info NT Path: \Device\HardDisk0\Partition1
2018-08-01 12:16:43, Info ===========================================================
2018-08-01 12:16:43, Info ESP partition size will be 104857600
2018-08-01 12:16:43, Info MBR2GPT: Validating layout, disk sector size is: 512 bytes
2018-08-01 12:16:43, Info BCD: Opening store. Flags: 0x0
2018-08-01 12:16:43, Info BCD: Store path: "\??\GLOBALROOT\device\harddisk0\partition1\Boot\BCD"
2018-08-01 12:16:43, Info BCD: Loaded hive at BCD00000000
2018-08-01 12:16:43, Info BCD: Opening object {9dea862c-5cdd-4e70-acc1-f32b344d4795}
2018-08-01 12:16:43, Info FindOSPartitions: Default boot entry: {6B5EAFC2-954A-11E8-888E-001A7DDA7113}
2018-08-01 12:16:43, Info BCD: Opening object {6b5eafc2-954a-11e8-888e-001a7dda7113}
2018-08-01 12:16:43, Info VERBOSE: Device path: \Device\HarddiskVolume5
2018-08-01 12:16:43, Info VERBOSE: Dos path: \\?\GLOBALROOT\Device\HarddiskVolume5
2018-08-01 12:16:43, Info FindOSPartitions: Volume name for the default boot entry: \\?\Volume{b4a23283-0000-0000-0000-100000000000}\
2018-08-01 12:16:43, Info BCD: BcdGetElementDataWithFlags: Failed to open key.Object: {6b5eafc2-954a-11e8-888e-001a7dda7113} Type: 14000008 Status: c0000034
2018-08-01 12:16:43, Info FindOSPartitions: No Recovery sequence found.
2018-08-01 12:16:43, Info FindOSPartitions: Default boot entry locale: en-us
2018-08-01 12:16:43, Info Bitlocker protection for C:\ is either off or suspended.
2018-08-01 12:16:43, Info Unique ID recap for volumes:
2018-08-01 12:16:43, Info Volume name: \\?\Volume{b4a23283-0000-0000-0000-100000000000}
2018-08-01 12:16:43, Info Unique ID size: 12
2018-08-01 12:16:43, Info MBR2GPT: System partition cannot be removed in full OS mode, leaving it untouched.
2018-08-01 12:16:43, Info MBR2GPT: Trying to shrink the OS partition

I have a SanDisk SSD

I noticed that when I try to shrink Volume via Disk management it just hangs on the next window, the Activity Monitor shows a Service Host: Disk Defragmenter / Optimize drives process tat is using 10% CPU, has a growing memory usage as well as about 10MB/s disk usage

The exact same thing happens when the MBR2GPT process is "stuck" on Trying to shrink the OS partition
I partitioned the disk using a 3rd party software and create a 2GB Unallocated sector and tried again, same issue.

I also remove the 2 recovery partition on the drive. (I have a USB disk with the windows recovery system)
I am not sure what is going on, but I would really hate to do a complete wipe of the drive and start from scratch.

I welcome any ideas at this point.

[#45]

I gave it some time and now it failed:

2018-08-01 12:52:50, Info MBR2GPT was explicitly asked to run in full OS mode.
2018-08-01 12:52:50, Info MBR2GPT: Attempting to convert disk 0
2018-08-01 12:52:50, Info MBR2GPT: Retrieving layout of disk
2018-08-01 12:52:50, Info MBR2GPT: Initial partition information
2018-08-01 12:52:50, Info ===========================================================
2018-08-01 12:52:50, Info Partition layout for disk: 0
2018-08-01 12:52:50, Info Partition style : MBR
2018-08-01 12:52:50, Info MBR signature: 3030528643
2018-08-01 12:52:50, Info Number of partitions : 1
2018-08-01 12:52:50, Info ===================PARTITION===============================
2018-08-01 12:52:50, Info Number: 1
2018-08-01 12:52:50, Info Type: 7
2018-08-01 12:52:50, Info Boot: Yes
2018-08-01 12:52:50, Info Recognized: Yes
2018-08-01 12:52:50, Info Style: 0
2018-08-01 12:52:50, Info Offset: 1048576
2018-08-01 12:52:50, Info Length: 957941284864
2018-08-01 12:52:50, Info Volume: \\?\Volume{b4a23283-0000-0000-0000-100000000000}\
2018-08-01 12:52:50, Info Drive: C:\
2018-08-01 12:52:50, Info NT Path: \Device\HardDisk0\Partition1
2018-08-01 12:52:50, Info ===========================================================
2018-08-01 12:52:50, Info ESP partition size will be 104857600
2018-08-01 12:52:50, Info MBR2GPT: Validating layout, disk sector size is: 512 bytes
2018-08-01 12:52:50, Info BCD: Opening store. Flags: 0x0
2018-08-01 12:52:50, Info BCD: Store path: "\??\GLOBALROOT\device\harddisk0\partition1\Boot\BCD"
2018-08-01 12:52:50, Info BCD: Loaded hive at BCD00000000
2018-08-01 12:52:50, Info BCD: Opening object {9dea862c-5cdd-4e70-acc1-f32b344d4795}
2018-08-01 12:52:50, Info FindOSPartitions: Default boot entry: {6B5EAFC2-954A-11E8-888E-001A7DDA7113}
2018-08-01 12:52:50, Info BCD: Opening object {6b5eafc2-954a-11e8-888e-001a7dda7113}
2018-08-01 12:52:50, Info VERBOSE: Device path: \Device\HarddiskVolume5
2018-08-01 12:52:50, Info VERBOSE: Dos path: \\?\GLOBALROOT\Device\HarddiskVolume5
2018-08-01 12:52:50, Info FindOSPartitions: Volume name for the default boot entry: \\?\Volume{b4a23283-0000-0000-0000-100000000000}\
2018-08-01 12:52:50, Info BCD: BcdGetElementDataWithFlags: Failed to open key.Object: {6b5eafc2-954a-11e8-888e-001a7dda7113} Type: 14000008 Status: c0000034
2018-08-01 12:52:50, Info FindOSPartitions: No Recovery sequence found.
2018-08-01 12:52:50, Info FindOSPartitions: Default boot entry locale: en-us
2018-08-01 12:52:50, Info Bitlocker protection for C:\ is either off or suspended.
2018-08-01 12:52:50, Info Unique ID recap for volumes:
2018-08-01 12:52:50, Info Volume name: \\?\Volume{b4a23283-0000-0000-0000-100000000000}
2018-08-01 12:52:50, Info Unique ID size: 12
2018-08-01 12:52:50, Info MBR2GPT: System partition cannot be removed in full OS mode, leaving it untouched.
2018-08-01 12:52:50, Info MBR2GPT: Trying to shrink the OS partition
2018-08-01 13:24:29, Info MBR2GPT: Partition final size is: 957836427264
2018-08-01 13:24:29, Info MBR2GPT: Creating the EFI system partition
2018-08-01 13:24:29, Info Initializing VDS service
2018-08-01 13:24:29, Info Obtaining the VDS disk interface
2018-08-01 13:24:29, Info Retrieving the VDS disk properties
2018-08-01 13:24:29, Error PreparePartition: cannot format partition. Error: 0x00000000, async error: 0x80070057[gle=0x000036b7]
2018-08-01 13:24:29, Error Cannot create EFI system partition. Error: 0x000036B7[gle=0x000036b7]
2018-08-01 13:24:29, Info MBR2GPT: Partition information at error point
2018-08-01 13:24:29, Info ===========================================================
2018-08-01 13:24:29, Info Partition layout for disk: 0
2018-08-01 13:24:29, Info Partition style : MBR
2018-08-01 13:24:29, Info MBR signature: 3030528643
2018-08-01 13:24:29, Info Number of partitions : 1
2018-08-01 13:24:29, Info ===================PARTITION===============================
2018-08-01 13:24:29, Info Number: 1
2018-08-01 13:24:29, Info Type: 7
2018-08-01 13:24:29, Info Boot: Yes
2018-08-01 13:24:29, Info Recognized: Yes
2018-08-01 13:24:29, Info Style: 0
2018-08-01 13:24:29, Info Offset: 1048576
2018-08-01 13:24:29, Info Length: 957836427264
2018-08-01 13:24:29, Info Volume: \\?\Volume{b4a23283-0000-0000-0000-100000000000}\
2018-08-01 13:24:29, Info Drive: C:\
2018-08-01 13:24:29, Info NT Path: \Device\HardDisk0\Partition1
2018-08-01 13:24:29, Info ===========================================================
2018-08-01 13:24:29, Info MBR2GPT-undo: Extending back the OS partition
2018-08-01 13:24:29, Info MBR2GPT: Conversion failed

[#46]

Do you have the same problem when running MBR2GPT from WinPE? Chances are, you have something running in the full OS that is causing the issue and this is why it is recommended to run MBR2GPT in WinPE.

[#47]

I was finally able to complete the process.

I did this through the OS, not in PE.

The issue is really with how the process went on my SSD.

It was analyzing it for a while, like a good hour.

But, before the last time I tried it, when it worked, I used the Defragmenter tool to "optimize" my SSD, then it did the same thing, but now it worked. I can post the logs if it is going to help anyone.

I did have a boot problem, my BCD was effed up.

For this I did you WinPE and had to do the assign a letter to the EFI partition, then do the bcdboot c:\windows /s e: command to get the BCD stuff from the installed windows to the EFI partition, now it boots and switched the GPT so all is well.

[#48]

worked for me like magic !!! deleted one partition using diskpart tool in cmd prompt and voila !! thank u

[#49]

worked for me like magic !!! deleted one partition using diskpart tool in cmd prompt and voila !! thank u

[#50]

I Had the same error while trying to convert my mbr hard disk to gpt.
what I did for getting success was the following:
1.- checking my partitions in computer management, I saw my two partitions (system reserved and OS ) were primary partitions, but data partition Or D: (as I use to call it) was in logical partition state.
2.- I installed Minitool Partition Wizard and converted logical partition to primary.
3.- Run into windows Enviroment the mbr2gpt /convert /disk:"number of the disk" /allowFullOS and the... IT WORKED!

Hope you Found this helpful.

[#51]

I Had the same error while trying to convert my mbr hard disk to gpt.
what I did for getting success was the following:
1.- checking my partitions in computer management, I saw my two partitions (system reserved and OS ) were primary partitions, but data partition Or D: (as I use to call it) was in logical partition state.
2.- I installed Minitool Partition Wizard and converted logical partition to primary.
3.- Run into windows Enviroment the mbr2gpt /convert /disk:"number of the disk" /allowFullOS and the... IT WORKED!

Hope you Found this helpful.

[#52]

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.