Hi Charlie, I know that you said that you tried all the fixes suggested, but I just want to make sure we know what was suggested and what wasn't. First, could you try the solutions in the following article and see if any of them help: Websites don't load - troubleshoot and fix error messages

If the problem still exists, please let us know.

Hi Chris, I've since worked out that it it only happening on one user account on my mac. So I'm guessing I need to do a factory reset of Firefox or something similar. Is there a walkthrough of how to do that? I tried uninstalling and reinstalling using App Cleaner to remove all the entries, but it seemed to keep something on the computer as I was auto logged back into my account straight away.

Charlie

Hi Charlie, Try refreshing Firefox. This will purge a lot of your Firefox files, while retaining most of your personal data. For instructions, check out the following article: Refresh Firefox - reset add-ons and settings

Funnily enough, I just found this setting in Firefox this morning, but it seemingly isn't mentioned as a possible fix in the "websites load in other browsers but not Firefox" support article. Did I miss something? If not then I really think it should be.

Bottom line is that it worked and Firefox is now back to full strength.

Thanks Chris!