[Solved]Debian 10 don't boot:mount /mnt failed

[coco45]

Good evening
I just installed deb10 buster on an existing partition sda4 (replacement of another linux) in csm mode (no uefi partition)
I had no problems during the instal,I understand GRUB was not installed by debian.
I have 3 linux in multiboot,and after debian install I launch boot repair with my main linux ,and debian is now in the grub menu.
But infortunately during the boot such error occurs:
Mounting /dev/sda4 on root failed:no such device......
Busybox v1.30.1(debian 1 1 30 1 4) built in shell

[Head_on_a_Stick]

What happens if you type exit and press <return>? Please post any error messages that appear.

[Deb-fan]

Random thoughts, you might want to re-install the grub2 bootloader onto the bios/CSM Nix OS, then restore the OS you want to be controlling it again to put things back as you prefer The system does have an ESP partion on it though ? Meaning other installs are installed/booting in uefi-mode alongside this bios OS? Are secureboot, fastboot disabled in the pc's bios-uefi ? Are you sure that CSM even is ?

Lastly would search out Rod Smith's site, he's the person behind rEFInd and has mucho information about multibooting gnu/Nix in whichever modes. Noticed he had many postings, bunch of places online which may help someone in regards the subject. Many more focused on multibooting uefi/csm-etc along with Windows, still could be the info you need.

[coco45]

thanks for the two replies but I reinstall completely with a new download through the net install this time ( previously it was a live USB ) ; it takes a lot a time ( 50 mn ) but now it works and grub is correctly installed detecting my two others linux ....So far all is going right.

[Deb-fan]

^ Sounds like a nice setup, ... good deal.

[metreo]

Overall I appreciate how easy the bootloader install process is under Debian, tends to work smoothly even on newer drives