This doesn't occurred in 14w32b and not all worlds.

LAN was opened on a specific world and another player could enter the world and was visible in the world, but got kicked out in a split second with this error:

Internal Exception: io.netty.handler.codec.DecoderException:java.io.IOException: Packet 0/28 (kw) was larger than I expected, found 10 bytes extra whilst reading packet 28.

Is my specific world corrupt (it still works for other players to join, if I go back to 14w32b) or is it something else perhaps?