sudo apt-get update && sudo apt-get upgrade
sudo apt autoremove
sudo apt dist-upgrade
Make sure that’s nothing pending and everything up to date
sudo apt install update-manager-core
sudo do-release-upgrade
Throughout the installation there will be prompts to ask to overwrite or use the existing.
the first one will be PAM configuration override local changes to /etc/pam.d/common-*/ select “override“
The rest can be default.
After a few hours the installation will be done.
After restart there’s a chance that a ubuntu is unable to access network.
Go to /etc/resolv.conf change the existing nameserver from 127.0.0.53 to something either your own DNS IP.
CY - Technical Memory extension 