ros melodic unment dependencies

Question

I'm trying to install ros melodic on ubuntu 18.04 following instructions in this page http://wiki.ros.org/melodic/Installation/Ubuntu, when I use this command sudo apt install ros-melodic-desktop-full I get the following message

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 ros-melodic-desktop-full : Depends: ros-melodic-desktop but it is not going to be installed
                            Depends: ros-melodic-perception but it is not going to be installed
                            Depends: ros-melodic-simulators but it is not going to be installed
                            Depends: ros-melodic-urdf-sim-tutorial but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

I tried to install ros-melodic-desktop but it keeps giving me dependencies error messages. Any help, please.

Answer 1

sudo apt-get autoremove

if this doesn't work then just reinstall ubuntu. That's a faster way of get rid of these issues.