Since yesterday, Mozilla pushed in the official update channel of Firefox (now version 51) the latest version of Developer Tools. Why is this so important? Because right now, the Firebug extension is no longer supported. (*ding* to web developers and automation engineers)
As per the official blog post, you are invited to update to the last and greatest version.
Now, I’m still facing the issue where the Firepath extension is now longer usable with the actual DevTools. A quick solution this topic is to disable the Electrolysis (e10) in the Firefox settings. More about that in a future post 🙂
Update: Here is the guide