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Thread: Booting to Windows 10 completely removes GRUB

  1. #1
    Join Date
    Jun 2020

    Booting to Windows 10 completely removes GRUB

    I'm currently running dual boot with Windows 10 and Ubuntu 20.04 LTS. Each time after booting to windows grub gets deleted and I'm unable to boot. Using boot-repair solves problem, but only till i try to boot windows again. When using boot-repair it says that some error occurred during repairs, but still is solves problem temporarily.
    my boot info

  2. #2
    Join Date
    Jun 2009
    SW Forida

    Re: Booting to Windows 10 completely removes GRUB

    What brand/model system?

    Ubuntu lets you install in UEFI boot mode to MBR drives, Windows does not.
    You have Ubuntu on sda which is MBR(msdos) but boots in UEFI mode from ESP - efi system partition on sdb.
    It would be better but not absolutely required to have sda be gpt. But converting normally erases it. There are tools to convert, but still required good backups and reinstall of grub bootloader as UUIDs change.

    Some like HP only let you change boot order with UEFI settings. Grub uses efibootmgr & it works for one boot.
    Boot-Repair in line 89 has another suggestion to add info to Window's bootmgr.
    For more info on UEFI boot install & repair - Regularly Updated :
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  3. #3
    Join Date
    Jun 2020

    Re: Booting to Windows 10 completely removes GRUB

    Its custom build PC. I actually tried adding info to windows' bootmgr myself before writing here using command provided in boot-repair but it didn't work. Tried it again now since you mentioned it and it appears to have solved my problem. Don't know why it didn't work the first time. I have rebooted several times into different systems without any problems, so it seems to be solved. Thanks for help.


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