btrfs filesystem apparaît et dure un moment pendant le boot.

La solution : The solution requires two steps.

Remove from fstab the partition(s) that no longer exist. To do this, run blkid in the terminal. Then open /etc/fstab with root privileges and look for the UUID(s) that were not listed by blkid. Delete the line(s) that contain those UUID(s). Save and close.

Run this command in terminal :

sudo update-initramfs -u

That should fix it. AFAIK this second step is required only in the Ubuntu-type distros.

Solution trouvée ici, voir en bas de la page