When connecting to my server, i experienced the error:
EXCEPTION:JAVA.IO.IOEXCEPTION:RECEIVED STRING LENGTH LONGER THAN MAXIMUM ALLOWED (19>16)
I did some testing and worked out that this was because I'd made some custom prefixes for the team names in that world's scoreboard.dat, and while it worked in single player, since the string length was too long, putting the world on my server didn't work.
As far as I can tell, the only fix necessary is increasing the maximum string length allowed for prefixes and suffixes for teams in scoreboard.dat. I understand that at the moment the only things that the scoreboard prefixes and suffixes are used for is the colored names, but keeping the string limit at 16 will break some maps in multiplayer.