I want to install some applications/ packages that were available for Ubuntu 18.04 on Ubuntu 18.10. In my special case it is the Deepin Desktop Environment, but there are other packages, too.
From the instructions on the net I learned to do it with the following commands in the terminal:
sudo add-apt-repository ppa:leaeasy/dde -y sudo apt-get update sudo apt-get install dde
Then I get the following output/ error message:
Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package dde
I figure that either Ubuntu or Deepin are not maintaining the package.
My question is: is it possible - speaking in general terms, not only for this specific application - to install a package of an older version on a newer version, when the package cannot be located in the repositories of the newer version? If yes, what would be the proceedings?