When placing down a sign all online (at least those within maybe 30 blocks of the sign) clients crash. The message the clients receive are as follows: "...gson.MalformedJsonException... JSON at line 1 column 2"(http://supa.me/EAOxOU.png).
The console spams the following error (https://gist.github.com/SupaHam/e024d2be25622576a33c).
P.S. Restarting the server does not fix anything.
Environment
Server: java version "1.8.0_45"
For what it's worth. Getting kicked in general displays that client error. so I'm assuming the actual bug causing the crashing is not something I can track or help you track down on my end.