Release upgrade
ex. 18.04.x -> 20.04
$ sudo do-release-upgrade -d
Minor upgrade 16.04.x -> 16.04.3
ex. 16.04.2 -> 16.04.3
20.04, Not available now.(June 10)
DeskTop:
$ sudo apt install --install-recommends linux-generic-hwe-16.04 xserver-xorg-hwe-16.04
Server:
$ sudo apt install --install-recommends linux-generic-hwe-16.04