kelvin@orz:~$ sudo do-release-upgrade
Checking for a new Ubuntu release
There is no development version of an LTS available.
To upgrade to the latest non-LTS develoment release
set Prompt=normal in /etc/update-manager/release-upgrades.
kelvin@orz:~$ lsb_release -d
Description:    Ubuntu 18.04.4 LTS
kelvin@orz:~$