Unable to parse jason returnde by the server, in file ext-all.js

I'm running some programming example's and the server send me this message: [WARN]Unable to parse json returnde by the server.

I'm using xampp stack in ubuntu 14.04, the warning points to the file ext-all.js, the page can't connect with the database. please help!!

the code is in the ext-all.js file! i didn't touch the file!