ROS download unable to locate package error

Solution 1:

1. Make sure to configure your Ubuntu repositories to allow restricted, universe, and multiverse. See this for a guide on how to do that.

2. Issue the following command into terminal to setup your computer to accept software from packages.ros.org

   sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'
   

3. Setup your keys by issuing the following into terminal:

   curl -sSL 'http://keyserver.ubuntu.com/pks/lookupop=get&search=0xC1CF6E31E6BADE8868B172B4F42ED6FBAB17C654' | sudo apt-key add -
   

4. Update your packages

   sudo apt update
   

5. Now install:

   sudo apt install ros-melodic-desktop-full