When you convert an 1.8.x or earlier world to 15w31a or 15w31b, you disconnect with JSON error every time you approach a sign etc. or with a message telling you to set JSON parsing to lenient.
When you convert an 1.8.x or earlier world to 15w31a or 15w31b, you disconnect with JSON error every time you approach a sign etc. or with a message telling you to set JSON parsing to lenient.
Got the same issue and can confirm it.
In singeplayer everything works fine, all the Signs are loading.
As soon as I put the world onto a 15w31b Server, it won't let me in.