How do I fix this error when trying to install packages?

Question

I can't install packages because of an unknown error.

$ sudo add-apt-repository -y ppa:otto-kesselgulasch/gimp
$ sudo apt-get update
$ sudo apt-get install gimp
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 gimp : Depends: libgimp2.0 (>= 2.8.18) but it is not going to be installed
        Depends: libgimp2.0 (<= 2.8.18-z) but it is not going to be installed
        Depends: gimp-data (>= 2.8.18) but it is not going to be installed
        Depends: gimp-data (<= 2.8.18-z) but it is not going to be installed
        Depends: libbabl-0.1-0 (>= 0.1.10) but it is not going to be installed
        Depends: libgegl-0.3-0 (>= 0.3.0) but it is not going to be installed
 xdgurl : Depends: python-tk (>= 2.7.0) but it is not going to be installed
          Depends: python3-tk (>= 3.2.0) but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

Answer 1

The script says "You might want to run 'apt-get -f install' to correct these". Have you tried running sudo apt-get -f install? It will attempt to correct broken dependencies. Afterwards, you would want to try to install each of those programs on which GIMP depends (that's what makes them dependencies).

Answer 2

Try to run sudo apt-get update then folowed by sudo apt-get install -f