Hi,
After installation of UrBackup agent for Linux Ubuntu I got the same error when booting into Linux Ubuntu pc.
Linux Ubuntu pc couln’t boot properly and was stuck in initramfs ash shell.
some kind of new boot partition was created which overrode all menuentries inside /boot/grub/grub.cfg, all /dev/sda3 entries were replaced by
/dev/mapper/root-96d1f8c1f425
unfortunately I couldn’t fix this issue using commands in grub because I was stuck on below error and couldn’t quite get around that
linux /boot/vmlinuz-6.5.0-35-generic root=/dev/sda3
error: can’t allocate kernel.
boot
error: you need to load the kernel first
However, steps described in this topic helped me solve my problem.
Also additional important fix is to just manually overwrite every occurrence in /boot/grub/grub.cfg of /dev/mapper/root-96d1f8c1f425 by /dev/sda3 (or other partition where is Your whole Linux filesystem)
and then try to avoid updating grub. After overwriting grub.cfg Linux will stop booting into /dev/mapper/root-96d1f8c1f425
Just in case someone else stumbles upon similar problem, here is some other useful information about grub
useful grub commands
to make it possible to scroll down in file contents using cat
set pager=1
to display all set variables
set
lsmod
displaying the drives/partitions in grub
ls
example of displaying content of partitions in grub
ls -al (hd0,1)/
example of displaying files in grub
cat (hd0,1)/boot/grub/grub.cfg
reinstalling grub
sudo grub-install /dev/sda
boot-repair utility
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt update
sudo apt install boot-repair
boot-repair