i just tried to create a new world...hope crash report is enough, and be fixed
crash-2017-05-14_20.53.15-server.txt
but it didn't happen again, ( i think so (can't say it won't happen) ).

no it doesn't. i will repoen this issue if it happens again..

Does it happen every time? Because this has never happened before, and it doesn't make any sense either :^)