This is actually for version 2.1, but according to this bug report function, that version doesn't exist, despite the fact it is what I have loaded currently.

A friend used to be able to join my game but cannot now. Another  friend who joins cross platform through Microsoft account from Xbox can still join. When the affected friend tries to join he gets the mentioned error. We have tried everything listed. He doesn't appear in my list of people in the game, so I cannot kick him out. I've quit and restarted multiple times. I've turned multiplayer off, signed in, signed out, turned multiplayer back on. I've deleted my logs. We both have updated. We both have deleted the game and reinstalled. I've signed out of my Microsoft account. He tried making a Microsoft account and joining through that account rather than as a PS friend. We can't get it to work. What can we do?