I have used kubuntu(10.04 & 12.04) and firefox for many years. Recently I upgraded to 14.04 and firefox will no longer open local html files. I installed chromium and it seems to work properly. Since firefox has always been my preferred browser is anyone aware of a fix for this problem?
Yeah, please share what is the exact error that you experience.
By the way, you could possibly try resetting the settings in Firefox. To do so, go to the new config menu, open the Help menu, and then Troubleshooting Information. Click Reset Firefox. And then check whether you are able to view local html files.
Firefox will reset all your data (including addons, themes and profile data), and your Firefox installation will be like a brand new one. If everything works fine, then you can re-install your favorite addons.
Otherwise, you could try deleting (or backing up) your profiles directory, which is housed in $HOME/.mozilla/firefox.