Resolving converting MBR to GBT converting boot issue

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  1. Posts : 98
    Windows10
       #1

    Resolving converting MBR to GBT converting boot issue


    I'm trying to upgrade Windows10 (Build: 21H1) to Windows11 since I have to convert the MBR to GBT that is where the issue begins. I've tried to do this both online and offline to no success.
    This is the error which I get related to someone else had on this page but only when attempting to do the conversion using mbr2gbt offline using a Windows rescue disk in command prompt. When I attempt to do the conversion online, that is within Windows, this is the error code I get;
    Code:
    MBR2GPT: Attempting to convert disk 3MBR2GPT: Retrieving layout of diskMBR2GPT: 
    Validating layout, disk sector size is: 512 bytesMBR2GPT: 
    Trying to shrink the OS partitionMBR2GPT: 
    Creating the EFI system partitionCannot create EFI system partition. 
    Error: 0x000036B7
    MBR2GPT-undo: 
    Extending back the OS partition
    MBR2GPT: Conversion failed
    I prefer to do this offline, but based on this page and this page, the solutions seem to fall into my situation but not exactly. The second link which was just posted, makes me wonder if the boot is spread out over two disks, not that is may be for my situation but it was mentioned ?

    Therefore I understand when doing the conversion offline diskpart is a necessity; it's just knowing what has done wrong with my particular boot that the conversion isn't smooth and how to convert it and fix the boot issues so that it will convert. All this while not loosing any data as mbr2gbt is capably off; although I know a backup prior to doing this is important.
      My Computer


  2. Posts : 23,202
    Win 10 Home ♦♦♦19045.4291 (x64) [22H2]
       #2

    @JerometheGiraff

    You'll need to post a screenshot of Disk Management, stretched out sideways so we can read all the writing on the top and the bottom sections.


    How to Post a Screenshot of Disk Management
      My Computer


  3. Posts : 5,329
    Windows 11 Pro 64-bit
       #3

    Looks like EFI system partition cannot be created you can do it manually if you like in this video, i will show you how to create EFI partition from within Windows Recovery Environment.

      My Computer


  4. Posts : 18,432
    Windows 11 Pro
       #4

    FreeBooter said:
    Looks like EFI system partition cannot be created you can do it manually if you like in this video, i will show you how to create EFI partition from within Windows Recovery Environment.
    Shouldn't the drive be GPT first? Yes, it is possible to boot an MBR drive in UEFI mode, but it is not supported by Microsoft. Windows major updates will fail, and I am fairly sure the upgrade to Windows 11 will fail if the drive is not converted to GPT first. And you can't create a true EFI System Partition on an MBR drive, you can create a FAT32 partition with the files in it required to boot in UEFI mode.
      My Computer


  5. Posts : 4,572
    several
       #5

    There are 3rd party partitioners that can convert mbr>gpt without data loss.

    I have done it many times.

    If you post a screenshot of disk management window or similar it would be helpful.
      My Computer


  6. Posts : 98
    Windows10
    Thread Starter
       #6

    FreeBooter said:
    Looks like EFI system partition cannot be created you can do it manually if you like in this video, i will show you how to create EFI partition from within Windows Recovery Environment.

    I don't want to do the converting online, if that is what you meant ?
      My Computer


  7. Posts : 18,044
    Win 10 Pro 64-bit v1909 - Build 18363 Custom ISO Install
       #7

    Hello @JerometheGiraff,

    JerometheGiraff said:
    I don't want to do the converting online, if that is what you meant ?
    It is NOT performed 'Online'.

    You Boot from an installation USB into the Advanced Startup Options and then perform the Diskpart commands.

    Have a look at this . . .

    > How to Boot to Advanced Startup Options in Windows 10

    I hope this helps.
      My Computer


  8. Posts : 98
    Windows10
    Thread Starter
       #8

    Here is the screen shot of my disk management window, I hope it helps !

    https://i.postimg.cc/gkNyDxGk/diskmgmtwindow.jpg
      My Computer


  9. Posts : 18,044
    Win 10 Pro 64-bit v1909 - Build 18363 Custom ISO Install
       #9

    Hello @JerometheGiraff,

    JerometheGiraff said:
    Here is the screen shot of my disk management window, I hope it helps !
    I am sorry, but it is so small that we can NOT read it !
      My Computer


  10. Posts : 6,300
    Windows 11 Pro - Windows 7 HP - Lubuntu
       #10

    To do a offline conversion, you should boot from a Win 10 Installation drive. At the Windows Setup screen, press Shift+F10 simultaneously to open a command line prompt and run mbr2gpt.

    As already asked, please post a whole window Disk Manager image of your drives. Don't forget to expand the columns so we can read them. How to Post a Screenshot of Disk Management
    If you have a MiniTool or AOMEI Partition use it instead or Windows disk manager.
      My Computers


 

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