Solve Boot Problems: The Kernel Did Not Find the Root Partition Using its UUID

On startup the system hung because the root UUID was not found.

So when I ran sudo blkid — executed from a live cd — it didn't show the root partition (all other partitions UUIDs were listed).

But tune2fs showed me its UUID

sudo tune2fs -l /dev/sda2

So I tried to set a new UUID:

# with uuidgen's result:
sudo tune2fs /dev/sda2 -U a72d5565-b5fd-4e15-bfa8-8067e6bdfbc8

This didn't help.

What helped

... was to set linux [...] root=/dev/sdaX [...] in the grub2 settings.