Still appears to be an issue in 17w17a, However I've never had a crash when there are no players on the server, Perhaps the crash only happens when players are online?
Seems to be more common now in 17w15a and 17w14a, possibly breaks on more than just connection issues now?
Just had this happen on a vanilla 1.11.2 server.
Still a thing for 17w06a
Unfortunately still a thing in 1.11.2; had a script to run a bunch of RCON commands from a text file and this is the crash I get.
http://pastebin.com/raw/3uUR383P
I don't think so, it could just be the OS I'm using and if not it'd probably need a new ticket for the real issue anyway.
I found the problem, It seems in multiplayer you can not use capital letters in folder/file names but in Single Player you can.
(And I did test & confirm moving the world from single player to multiplayer does not work)
It works as expected in my singleplayer world.
Confirmed for 1.8.7 as well.
Also affects the full release 1.13