[SEVERE] Reached end of stream for / IP

I downloaded the 13w21b Server snapshot..
turned the server on, connected to it the first time, than i was just playing around, and i quit out of the server and the next time i joined it said "End Of Stream" and in console "[SEVERE] Reached end of stream for / IP".

To fix it every time i have to restart the map

Please help i can't play snapshot with my friends

Thanks, anyway!