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