Thanks a lot for your help @mardy and @dobey ! 🙂 The older version of crossbuilder seems not to work either, as you predicted @mardy. But since OTA-5 just got released I think I'll spare myself from setting up Unity8 (at least for the moment) and will just wait till I receive the update and then try to build for 16.04. Again a big thank you to both of you and have a nice day! 🙂