When I was gonna fly up with my elytra, 50m later it said "Invalid move Player Packet Recieved", and i was taken to the multiplayer screen weirdly, even when i made it in singleplayer!
I went back in the world, i was going down with the Elytra, and it kept saying it, and i couldn't do anything to stop it.
This still happens to me, in version 18w10d