Please switch your /etc/apt/sources.list file to use "http://old-releases.ubuntu.com" instead of "http://archive.ubuntu.com". After doing that you'll be able to run 'apt update' and 'apt dist-upgrade' to install all available updates for your release. Finally, you'll be able to run the distribution upgrade to Ubuntu 22.04 LTS.
Please switch your /etc/apt/ sources. list file to use "http:// old-releases. ubuntu. com" instead of "http:// archive. ubuntu. com". After doing that you'll be able to run 'apt update' and 'apt dist-upgrade' to install all available updates for your release. Finally, you'll be able to run the distribution upgrade to Ubuntu 22.04 LTS.