console.log() doesn’t work anymore in Firebug since Firefox 51.0.1
As I mentioned in another answer, this happens because the Firefox internal APIs, which Firebug uses to output the data, have changed. When you open the Browser Console, you’ll see the following error: TypeError: ConsoleAPIListener is not a constructor console.js:149:38 Note that, as stated in a thread in the Firebug discussion group and on the … Read more