GRUB Repair

This is the go-to guide in case of grub issues. It could fail for many reasons:

• Having a dual boot could easily nuke your GRUB (e.g. getting into rescue mode). It happened in October 2024 after a Windows 11 update.

• After a GRUB config update that is incompatible with your current version of GRUB

If your system doesn’t boot

1. Boot into a ArchLinux ISO

2. Mount your system drives:

   fdisk -l
   # identify your boot, root and efi partitions
   
   mount /dev/nvme0n1p2 /mnt
   mount --mkdir /dev/nvme0n1p1 /mnt/boot
   mount --mkdir /dev/nvme0n1p3 /mnt/efi
   

4. chroot in the partition:

   arch-chroot /mnt
   

5. Install the required tools

   pacman -S grub efibootmgr os-prober dosfstools mtools ntfs-3g

6. Re-install grub and update the config:

   sudo grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB
   sudo grub-mkconfig -o /boot/grub/grub.cfg
   

7. Validate that your Windows install has been discovered:

   grep -i windows /boot/grub/grub.cfg
   

If your system is booting

1. Install the required tools:

   sudo pacman -S os-prober
   

2. Mount the EFI partition to detect your windows install:

   sudo fdisk -l | grep EFI
   /dev/nvme0n1p1       2048     534527     532480   260M EFI System
   
   sudo mount /dev/nvme0n1p1 /efi
   

3. Run os-prober:

   sudo os-prober
   

4. Create a backup of your current config:

   sudo cp /boot/grub/grub.cfg{,2024-10-20}
   

5. Re-install grub and update the config:

   sudo grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB
   sudo grub-mkconfig -o /boot/grub/grub.cfg
   

6. Validate that your Windows install has been discovered:

   grep -i windows /boot/grub/grub.cfg