How to make GPT volume bootable

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  1. jimbo45's Avatar
    Posts : 7,851
    Windows / Linux : Centos, Ubuntu, OpenSuse
       #11

    Hi there

    why are people so afraid of command line (OK I know I use Linux a lot but Windows also has decent command level stuff).

    use cmd in admin mode

    Diskpart
    list disk
    select disk nn
    clean
    convert gpt
    create partition efi size=100
    format quick fs=fat32
    create partition primary (rest of disk)
    format quick fs=ntfs

    Now disk is in correct format to copy partitions, install windows, use Rufus to create bootable whatever etc etc.

    Cheers
    jimbo
      My ComputerSystem Spec

  2. Caledon Ken's Avatar
    Posts : 15,716
    Windows 10 Pro x64 Build 1809
       #12

    jimbo the idea is to replace current EFI partition. This would delete entire drive, wouldn't it.
      My ComputerSystem Spec

  3. jimbo45's Avatar
    Posts : 7,851
    Windows / Linux : Centos, Ubuntu, OpenSuse
       #13

    Hi then
    simply go into any decent partition manager and just re-format the efi partition. KYHI's disk is good for that -- aomei partition assistant etc.

    After doing whatever you need to do if you have boot problems just use Macrium (also on KYHI's disk) to "Fix windows boot problems.

    I copied an old WINtoUSB W10 from AMD server to INTEL laptop internal HDD, fixed boot via macrium on the KYHI disk and all worked fine (W10 got new drivers no prob). I just couldn't get back to "non insider builds" on the laptop - for once forgot to take backup before getting insider builds !!! (Bad Boy !!!) but did have a WindowstoUSB bootable SSD of build 1803. After creating image and restoring to internals SSD and fixing boot - worked a treat.

    Cheers
    jimbo
      My ComputerSystem Spec


  4. Posts : 11
    Win 7 Pro
    Thread Starter
       #14

    As I was having problems creating a Win 10 bootable pen drive I took time to reformat the EFI partition and "Fix windows boot problems" as suggested above. When I power on I am told there is no boot disk.
    I tried the Win 8 startup repair but that failed.
    But from the Win 8 repair drive I can get to command prompt, select the disk and partition; but what now ? If this were MBR I could say 'active'. But for GPT ?

    P.S. No response to my thread on eightforums. Clearly this is the better.
      My ComputerSystem Spec

  5. Caledon Ken's Avatar
    Posts : 15,716
    Windows 10 Pro x64 Build 1809
       #15

    These are the directions for creating an efi from scratch. Since you have partition (EFI) you would select the partition, format it, give it a letter and run command

    bcdboot X:\windows /s S:

    Moving / recreating EFI partition


    I believe you have 8.1. If you want 10 then go to the Media Creation tool (MS), download tool, execute tool and it will create a USB key for you, need 8GB key.

    Create Bootable USB Flash Drive to Install Windows 10

    and here is how to clean install. Since you machine likely has product key loaded in UEFI it should just load.

    Clean Install Windows 10

    Does your device have COA sticker, might be in battery compartment.



    At least that is what I would do.
      My ComputerSystem Spec

  6. topgundcp's Avatar
    Posts : 2,447
    Ubuntu14.04x64 MintMate17x64 Win10Prox64
       #16

    Not sure if you got the problem resolved. If not then:

    IMHO, This is a simple fix. Obviously you are running Windows 8 based on the disk layout.
    Boot into Windows 8 Recovery. Open the Admin command prompt then type:
    mountvol U: /s
    del /s /f /q U:\efi\*.*
    bcdboot c:\windows /s U: /f UEFI
    mountvol U: /d

    Shutdown and Reboot


    1st command: UEFI firmware looks for EFI System Partition, mount it then assign the drive letter U:
    (More efficient than using diskpart).
    2nd command: Delete everything under U:\EFI folder
    3rd command: Rebuild the BCD to boot from. NOTE: Macrium does the same thing to fix the boot problems
    4th command: Unmount EFI System partition and unassign the drive letter U:

    NOTE: there's a space before the forward slash (/) in each command
      My ComputerSystem Spec



 
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