Looking directly up while flying with an elytra will cause the player's arms and legs to disappear, and they stop moving, and start floating down for 1 second before it kicks the player from the game and giving them the message, "Invalid move player packet received"
Players in survival will also take damage from this.
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Comments 4
This issue duplicates MC-122354?
Jup.

Yes, it just happened to me.
On a server, you get disconnected with the exception "Invalid move player packet received".
Interesting enough, the game output log doesn't show any error, tho