Major version upgrdae

Upgrade major version

apt update
apt upgrade -y
shutdown -r now
apt install update-manager-core

Check that upgrade is set to LTS (if that intention to stay with Long Term Support)

vi /etc/update-manager/release-upgrades

Prompt=lts

Perform upgrade

apt dist-upgrade
shutdown -r now

do-release-upgrade -f DistUpgradeView:Text

Clean

apt autoremove --purge -y

shutdown -r now
hostnamectl

apt autoremove --purge

software-properties

Do additional check for updates pending on major version upgrage

apt update
apt upgrade -y