$ LANGUAGE=C sudo apt-get install kubuntu-desktop -o  Debug::pkgProblemResolver=true
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Starting pkgProblemResolver with broken count: 1
Starting 2 pkgProblemResolver with broken count: 1
Investigating (0) kubuntu-desktop [ amd64 ] < none -> 1.332~ppa1 > ( metapackages )
Broken kubuntu-desktop:amd64 Depends on okular [ amd64 ] < none -> 4:15.08.2-0ubuntu3 > ( universe/graphics )
  Considering okular:amd64 2 as a solution to kubuntu-desktop:amd64 9999
    Reinst Failed early because of libokularcore6:amd64
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:
 kubuntu-desktop : Depends: okular but it is not going to be installed
                   Recommends: amarok but it is not going to be installed
                   Recommends: gtk3-engines-oxygen but it is not installable
                   Recommends: plasma-widget-kimpanel but it is not going to be installed
E: Unable to correct problems, you have held broken packages.