I restarted my machine (Ubuntu 20.04 LTS on Dell XPS) and got the gnu grub 2.04 screen, instead of booting up my operating system normally. As far as I can tell, I didn't do anything weird to my grub config file.

I tried booting linux manually on grub, using the tutorial found here.

I found a bunch of different partitions in grub:

grub> ls
(proc) (hd0) (hd0,gpt2) (hd0,gpt1) (hd1) (hd2) (hd2,gpt2) (hd2,gpt1)

After looking inside each one, I determined that I should be booting from (hd2,2), since it contains my file system:

grub> ls (hd2,2)/
lost+found/ boot/ swapfile etc/ media/ var/ bin dev/ home/ lib lib32 lib64 libx32 mnt/ opt/ proc/
root/ run/ sbin snap/ srv/sys/ tmp/ usr/ cdrom/

I continued to follow the tutorial:

grub> set root=(hd2,2)
grub> linux /boot/vmlinuz-5.4.0-39-generic root=/dev/sdc2
grub> initrd /boot/initrd-5.4.0-39-generic
grub> boot

In line 2 I chose /dev/sdc2, following the instructions in the tutorial: "How do you know the correct partition? hd0,1 = /dev/sda1. hd1,1 = /dev/sdb1. hd3,2 = /dev/sdd2. I think you can extrapolate the rest." I extrapolated that hd2,2 = /dev/sdc2.

The system did not boot, instead giving the message:

Gave up waiting for root file system device. Common problems:
 - Boot args (cat /proc/cmdline)
  - Check rootdelay= (did the system wait long enough?)
 - Missing modules (cat /proc/modules; ls /dev)
ALERT! /dev/sdc2 does not exist. Dropping to a shell!

I am not sure what to do from here. Any help would be appreciated.

  • The tutorial uses kernel version numbers like 5.4.0-39. Did you replace those by the ones on your system? You can just type vmlinuz and press Tab. – Jos Jun 30 at 15:16
  • Yes I replaced the numbers. My latest kernel is 5.4.0-39. I found it by looking at the contents of (hd2,2)/boot/. – user1873329 Jun 30 at 15:21

I did not determine what was wrong, but the Ubuntu boot repair tool seemed to fix things.

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