• Do i need to reinstall GRUB in my dual boot?


    Hey Antergos Community,
    So this is my first Linux experience and i’m semi ok with computers in general.
    I have a laptop, where i first installed windows 8.1, and afterwards installed antergos. Everything worked fine so far and i used the GRUB bootloader to access both systems. My system uses the EFI-boot, with an own partition.
    Sadly i had the stupid idea to create a new partition in Windows, which led to the following problem:
    Whenever i now start my pc i get greeted with:
    "Welcome to GRUB

    error: unknown filesystem"

    I actually figured out how to progress from here with the great help of google (Link: https://unix.stackexchange.com/questions/148041/recovering-from-grub-rescue-crash ) and i am actually able to start my old grub bootloader with no problems and boot into both of my systems from there. The commands i have to use to get GRUB on the screen are the following:

    grub rescue>  set boot=(hd0,gpt6)
    grub rescue>  set prefix=(hd0,gpt6)/boot/grub
    grub rescue>  insmod normal  
    grub rescue>  normal 
    

    The problem for me is now: How can i prevent the grub rescue from appearing everytime when i reboot?
    Things i have tried so far after more googling:

    sudo os-prober
    sudo grub-mkconfig -o /boot/grub/grub.cfg
    

    both work as a command and i thought they would fix my problem by repairing the GRUB, but the rescue still pops up everytime.
    Do i need to reinstall GRUB on my system now? (I googled for that, but i am a bit overwhelmed with the EFI part of https://wiki.archlinux.org/index.php/GRUB#.22Firmware_setup.22_menu_entry_.28UEFI_only.29 - do i really need to do all that stuff, or will sudo grub-install /dev/sda work, which i saw on a lot of threads?)
    Should i just remove my new partition from windows :D ?

    So sadly i am a bit overwhelmed how to procede from here and i hope, that someone from this community can help me somehow or lead me towards a solution. I hope i explained everything in an understandable way, my computer expertise is not the greatest and i am actually somewhat proud to even have made it past the GRUB rescue screen. 🤦♂

    Best regards, Nick

  • @nickhero said in Do i need to reinstall GRUB in my dual boot?:

    “Welcome to GRUB
    error: unknown filesystem”

    depending on how your system try to boot… secure boot needs to be disabled inside EFI-Bios and you should have EFI-Boot and not legacy aka Bios/MBR boot enabled .

    I am not shure what exactly causes the error because there are different solutions aviable on search mr. google for this error… (large hd with a lot of partition IS ONE)

    On a EFI Boot System you need to install grub NOT to MBR it needs to be installed like this:

    https://antergos.com/wiki/de/miscellaneous/how-to-fix-grub-with-efi-boot/

  • Hey, thank you very much!

    With the help of your link i was actually able to reinstall grub which seems to have solved my problem.
    Just for further documentation if someone else gets this problem:

    i booted my pc and got put into the GRUB rescue screen. From there i moved forward with the commands from my first post and booted into antergos.
    Here i opened a terminal and used the following commands:

    sudo fdisk -l
    

    Here i identified my /dev/sda2 as my EFI-Partition and /dev/sda6 as my root-Partition. (I’m not sure if i needed to do all steps that follow from here, but i did and they worked greatly.)

    sudo mount /dev/sda6 /mnt 
    sudo mount /dev/sda2 /mnt/boot/efi 
    sudo os-prober
    sudo grub-mkconfig -o /boot/grub/grub.cfg
    sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=Antergos-grub
    

    Afterwards i rebooted and my GRUB finally started in a normal way from here. No more GRUB rescue!

    So, thank you very much for your help @joekamprad :).

    Best regards,
    Nick

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