For some time now it seems that Firefox offline mode is broken or borked in some way.
I notice this on the train when I need to refer to Android documentation. Documentation can be downloaded as part of the Android developer kit. This used to work just fine in Firefox on my netbook when offline. Recently though, perhaps two releases of Firefox ago, it utterly fails.
Firefox displays nothing other than a blank white page whilst trying to connect to google.com or googleapis.com. Yesterday/today it has been particularly frustrating as I’ve been trying to work on stuff that I’ve not done before. Documentation was essential.
A search of the internet suggests that it might be add-on related. Some suggest restarting Firefox in safe mode. Disabling add-ons, safe mode make no difference. It is core Firefox that is at fault.
I have now installed Epiphany. It can open the local files, though the search function doesn’t seem to work. Better than nothing.