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.

Upgrading your profile from Release to Nightly, which occurs automatically when you open it with Nightly, is a one-way irreversible step. This could prevent your profile from being used with Release without crashes, or lose profile data such as bookmarks or saved passwords when later used with Release, depending on what work is underway in Nightly and if it happens to be backwards-compatible. Be sure to backup your profile if you choose to switch channels.

Note: I am told that Developer channel uses a separate profile, but there are instructions below showing people how to override that, at which point this warning becomes relevant once again.