I am trying to follow quick installation guide for GeoNode on Ubuntu 20.04 LTS. https://docs.geonode.org/en/2.8/tutorials/install_and_admin/quick_install.html
sudo add-apt-repository ppa:geonode/stable sudo apt-get update; sudo apt-get upgrade; sudo apt-get autoremove sudo apt-get install geonode
However, when I try to run last line, it shows me error: E: Unable to locate package geonode
If you look at the screenshot: there are already errors while adding repository, such as "E: The repository 'http://ppa.launchpad.net/ubuntugis/ppa/ubuntu focal Release' does not have a Release file." and others...
What could be the solution?