I had this problem on Ubuntu Mate (18.04). I resolved it by deleting the okularrc file in ~/.config/okularrc When you start okular again, it will create a fresh okularrc file.
I had this problem on Ubuntu Mate (18.04).
I resolved it by deleting the okularrc file in ~/.config/okularrc
When you start okular again, it will create a fresh okularrc file.