I am getting this error whenever I install any package from the terminal. What is wrong?
apt-get install gnome-tweak-tool Reading package lists... Done Building dependency tree Reading state information... Done Package gnome-tweak-tool is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'gnome-tweak-tool' has no installation candidate