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.
Maybe this solution helps somebody else.
This worked for me, i feel like you just saved me from hours of endless google searches. Thanks