testcase does not describe a Kubuntu/KDE/Discover friendly process. Seems to be written for a GNOME-specific GUI.
Used instead:
1. Install all updates available for the release you want to upgrade sudo apt update && sudo apt -y dist-upgrade
2. Ensure the upgrade process is looking for any new LTS version
Discover -> Settings > Software Sources > Updates > Release upgrade
OR
sudo software-properties-qt
3-4. Launch upgrade process
sudo do-release-upgrade -c -d
testcase does not describe a Kubuntu/ KDE/Discover friendly process. Seems to be written for a GNOME-specific GUI.
Used instead:
1. Install all updates available for the release you want to upgrade
sudo apt update && sudo apt -y dist-upgrade
2. Ensure the upgrade process is looking for any new LTS version
Discover -> Settings > Software Sources > Updates > Release upgrade
OR
sudo software- properties- qt
3-4. Launch upgrade process
sudo do-release-upgrade -c -d