My father once didn't catch a pokemon from a party challenge, and now when he tries to catch it the game crashes. The game doesn't allow him to create or join another party without catching the pokemon first, which of course is impossible.
No idea why this is happening. But if I'd have to guess, it's something along the lines of the game nit knowing what Pokemon is the reward, thus crashing it. Niantic plz fix.
by Perunajunior