Mozilla had released an update Saturday, but Sunday's fix is supposed to help more people who were affected. "There are some issues we're still working on, but we wanted to get this release out and get your add-ons back up & running before Monday", Mozilla said in a tweet Sunday.
Mozilla requires specific extensions digitally signed to improve security. The certificate Mozilla uses for that purpose expired, though, so Firefox started disabling extensions it no longer considered safe.
"No active steps need to be taken to make add-ons work again. In particular, please do not delete and/or reinstall any add-ons as an attempt to fix the issue", Kev Needham, Mozilla's product manager for add-ons, said in a blog post about the problem.
Saturday's fix updated Firefox using the studies tool for testing new features, which some have disabled. That fix didn't work for Firefox on Android or the slower-moving Extended Support Release (ESR) version of Firefox.
Sunday's fix was a more ordinary release of Firefox that repaired the certificate issue. It works for ordinary versions of Firefox for personal computers as well as the Android and ESR versions, Mozilla said.
As of this morning it still has not arrived for us.