"Repository does not have a release file" error [closed]
Solution 1:
You need to update your repository targets to the Eoan Ermine (19.10) release of Ubuntu. This can be done like so:
sudo sed -i -e 's|disco|eoan|g' /etc/apt/sources.list
sudo apt update
Solution 2:
As described here, you need to edit (as root) the file /etc/apt/sources.list (the easiest way to do this is to type sudo gedit /etc/apt/sources.list). On the line that mentions http://packages.ros.org/ros/ubuntu you need to add [trusted=yes] after the word deb (you might need to add it as a separate word). Then save the file and try again.