Hi, After you click '''Add Exception...''', the next window has an option to '''Permanently store this exception'''. If it is not enabled (ticked), the exception would be temporary. ............................................................................................................................... Useful links: [https://support.mozilla.com/en-US/kb/Options%20window All about Tools > Options] [http://kb.mozillazine.org/About:config Going beyond Tools > Options - about:config] [http://kb.mozillazine.org/About:config_entries about:config Entries] [https://addons.mozilla.org/en-US/firefox/addon/whats-that-preference/ What's That Preference? add-on] - Quickly decode about:config entries - After installation, go inside about:config, right-click any preference, enable (tick) MozillaZine Results to Panel and again right-click a pref and choose MozillaZine Reference to begin with. [https://support.mozilla.com/en-US/kb/Keyboard%20shortcuts Keyboard Shortcuts] [https://support.mozilla.com/en-US/kb/Viewing%20video%20in%20Firefox%20without%20a%20plugin Viewing video in Firefox without a plugin] [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder & Files] [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode] [https://support.mozilla.com/en-US/kb/Basic%20Troubleshooting Basic Troubleshooting] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes] [http://kb.mozillazine.org/Testing_plugins Testing Plugins] [https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins Troubleshooting Plugins]

Thanks! I then only add a request that Firefox/Mozilla clarify the buttons and text on those pages. The phrase "Add exception" sounds permanent. Add an extra button on the first page that allows for a quick, onetime exception. Note that it is also unclear for the user what non-permanent means in this context. Only one connection? Until the browser is closed? Or something else? As a follow up question, is there some about:config value I can set to make that "permanent" box unchecked by default?

The validity of the temporary exception is until the browser is closed. I have no idea about unchecking the box by default. I think it is the default feature now. But you can always override that in '''Tools''' ('''Alt''' + '''T''') > '''Options''' > '''Advanced''' > '''Encryption''' > '''View Certificates''' > '''Servers'''. Not sure of the consequences, but you can try to make the '''cert_override.txt''' of the profile read only.

Please also [https://addons.mozilla.org/en-US/firefox/addon/xulernia/ check this add-on.] Personally I've never used it. Please go through the reviews and ratings and the add-on support topics.