One day me computer (XPS 11 - 9730) didn't wanted to start ubuntu 18.04 again.

It dropped to the BusyBox and all fsck operations didn't helped.

The error on the screen:

Restart everything and dell recovery didn't worked for me.

The solution for my problem was to set the SATA Operation in the bios to AHCI.

DELL Bios:

Maybe this solution helps somebody else.

Cheers
Marc