When you try to mount something (eg. a horse or a boat) you will be kicked from the server and not be able to join again at this world. This issue is reproducable and occurs only in the multiplayer.
Environment
Jre7x64
MC-14479
player mount kicks you from multiplayer server
Resolved
Duplicate
0
Duplicate of MC-13623, please use the search function to see if your bug has already been submitted. Currently over 55% of tickets are being closed as duplicate.