If you're using an Elytra and facing straight up (###,# / -90,0), the world crashes and messages the player, "Connection Lost, Invalid move player packet recieved" and tells to go back to the server list.
I am currently testing on the new 18w07c snapshot.
Thank you for your report!
However, this issue is a Duplicate of MC-122354.
If you have additional information, please add it to that report.
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