I'm getting exporter error messages telling me that a Firefox preview cannot be shown. I just started getting it today while using r114 and r115 is no different. It also says the same thing about the other two browsers I have installed on my computer, Chrome and IE.
The browsers themselves still operate just fine. Construct 2 simply is no longer previewing anything for me.
Considering my "game" at this point - which I just began yesterday - consists of a background image and a cursor - I can't imagine the problems lies there.