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Aaron B's avatar
Aaron B
Copper Contributor
Mar 23, 2018

MBR2GPT Disk layout validation failed

When i try to run    mbr2gpt /validate /disk:0 /allowFullOS   i get the following output   MBR2GPT: Attempting to validate disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating ...
Palani Samy's avatar
Palani Samy
Copper Contributor
Jul 21, 2021
I was facing similar problem as my disk partition was in MBR format but I need it to be GPT format.
Disk validation failed.
Easiest way is solve this problem is as given below.
Go to Disk Manager -> Select disk (0 or 1 ) you want convert and select the partition eg. C -Drive
Right click --> Shrink the disk and put shrink value to 200MB ->OK
Go to CMD with admin mode run the below command
mbr2gpt /validate /disk:0 /allowFullOS -> Enter
Validation is success
Run below command to convert
mbr2gpt /convert /disk:0 /allowFullOS
Disk will be converted to GPT
Go to BIOS and change Legacy to UEFI mode and change boot sequence
Your system will boot with mfg logo













Blackskull's avatar
Blackskull
Copper Contributor
Oct 06, 2021

Palani Samy 

 

I have tried this 3 times with 3 fails.

 

C:\WINDOWS\system32>mbr2gpt /validate /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

C:\WINDOWS\system32>mbr2gpt.exe /convert /allowfullos

MBR2GPT will now attempt to convert the default book disk.
If conversion is successful the disk can only be booted in GPT mode.
These changes cannot be undone!

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

 

 

  • Palani Samy's avatar
    Palani Samy
    Copper Contributor
    Oct 07, 2021

    Blackskull 

     

    If you are trying convert a disk with operating system installed on it should boot properly with legacy boot mode then only converting MBR to GPT will work and  just having unallocated space will not convert but disk should be bootable in legacy mode fist .

    Existing OS (MBR) disk will have system reserved partition and OS partition .. 

     

    Please use migration software to take copy of existing OS disk and then convert.

    MBR to GPT there will  not be any data loss but reverse it-> you need delete the entire volume

     

    backup your data before proceeding.

     

    All the best 

     

    Regards,

    samy

     

     

     

     

     

  • Naeem86's avatar
    Naeem86
    Copper Contributor
    Oct 06, 2021
    Have you tried doing that from the recovery environment?

    I posted a link to instructions on how to do that.

    Also, please make sure your windows version is upto date.
    • Blackskull's avatar
      Blackskull
      Copper Contributor
      Oct 06, 2021

      Yes says I'm up to date. Naeem86 

      • Naeem86's avatar
        Naeem86
        Copper Contributor
        Oct 06, 2021
        Please check the actual windows version in system information, dont rely on windows update.

        I had a laptop that showed upto date but was runing version 1507. Had to update bios before able to update to latest version.

        Also, did you try instructions from the link?

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