I just updated the system on my wife’s computer… And it doesn’t load anymore. The GRUB item is missing from the start screen.
If you select any of the previous system snapshots (BTRFS), the system tries to start, but a line appears among the list of executed commands
Failed to start Remount Root and Kernel File System.
See 'systemctl status systemd-remount-fs.service' for details.
You need a computer to work and it’s just a disaster 
What could be the problem?
If you have the LTS kernel installed, you can boot those snapshots. If not, you can still restore them even if you can’t boot off them.
That being said, restoring a snapshot probably won’t fix grub being missing.
The LTS kernel is installed by default
Do I understand correctly that I should try to restore GRUB?
All EndeavourOS Linux entries?
Restore the entry would be possible from arch-chroot by reinstallation of the grub files after regenerating the grub.cfg. Question is what is the cause for the entry to disappear.
https://discovery.endeavouros.com/system-rescue/arch-chroot/2022/12/
https://discovery.endeavouros.com/system-rescue/repair-a-non-booting-grub/2021/03/
I don’t know the reason… The computer was working all day - there were no problems. Then I updated the system and overloaded it. And the GRUB item on the home screen is gone…
Yes, I have already booted from the bootable media. Now I’ll gather my strength and try…
sudo su to gain admin rights in terminal or run sudo before the commands !
mounted read-only 
sdb is your usb stick also
looks like /dev/nvme0n1p2 is the system and /dev/nvme0n1p1 the efi partition (ESP boot partition)
and as you said its BTRFS filesystem? so you need to mount the subvolumes.
sudo mount -o subvol=@ /dev/nvme0n1p2 /mnt
sudo mount /dev/nvme0n1p1 /mnt/boot/efi
as of grub it will be on /boot/efi in your fstab…
needs to unmount /dev/sdb1 before … or reboot into ISO
Apparently I’m doing something wrong at all - it doesn’t work out.
When I said that GRUB was missing, I meant this - the Endeavour record is missing
grub-mkconfig or grub-install should show errors if something is wrong.
I need a couple of minutes to do it again and take a picture.
efi partition is on 1 not 2
/dev/nvme0n1p1
my fault… partly…
sudo mount /dev/nvme0n1p1 /mnt/boot/efi
sudo umount /mnt/boot/efi
sudo mount /dev/nvme0n1p1 /mnt/boot/efi
sudo arch-chroot
…
It never even occurred to me to think that way.
I’ll try it again now
