Today I tried to fix an old issue with an old laptop having dual boot - windows / ubuntu. This issue occurred one day out of nowhere (someone from forums said it was caused by a windows update).

While the windows system still boots, the laptop cannot boot into ubuntu and always gets stuck at a grub rescue shell with an error:

file /boot/grub/x86_64-efi/normal.mod not found

The following steps helped me to boot into linux:

  • First, use command ls to see what partitions are available. The console will show a list of names such as (dh0,gpt1), (dh0,gpt2) etc.

  • Then, try to use ls command to find your linux partition by

    ls (dh0,gpt1)/

    In my case, ls (dh0,gpt9) gave me a list of familar folder names, e.g. boot, usr, opt etc.

  • Type the following commands and you should be able to boot.

    set root=(hd0,gpt9)
set prefix=(hd0,gpt9)/boot/grub
insmod linux
linux /vmlinuz root=/dev/sda9 ro
initrd /initrd.img
boot

After writing down this little post, I found out this page containing much better explanation of this process