All extensions disabled due to expiration of intermediate signing cert

There's a workaround that involves going to about:config and setting xpinstall.signatures.required to false.

However, if you're running the Stable or Beta version, it will only work under Linux. On Windows and MacOS you'll need to download Nightly or the Developer Edition.

To fix this on MacOS I did the following:

1. Downloaded and installed Firefox Nightly

2. Ran /Applications/Firefox\ Nightly.app/Contents/MacOS/firefox-bin --profilemanager

3. Changed the profile to "default" so my normal Firefox profile would be used

4. Started up Firefox Nightly, opened about:config, then set xpinstall.signatures.required to false

Not sure if it's a good idea to use my default profile in Nightly. It might be a wiser idea to copy it instead.