Such things happen when you do inter object connections and the object with the controller gets removed. This might even happen when one object is active (in an active layer) and the other is inactive (hidden layer).
But this is just a guess
ah ok, but this is without any layers, and just one scene, and nothing gets removed.
i was just building the script without any errors, after that i looked at my script and for what i had made, it was to long so i shortened it. and after that the error appeared.
and the error didn’t even come from inside the engine i think?
this because the error only appeared when u start the blender player, and its not even in between the blender start / end section… it gets printed above that.
anyway i am happy that it has been solved by making a new quest_handler again.