Mozilla screwed up and failed to renew the code signing certificate used for addons, resulting in mass-disabling virtually all addons for everyone. Yay. Even lightweight themes are affected, somehow, and they’re just glorified PNGs. Exactly one of the addons I have installed survived the armagadd-on, which is literally what Mozilla is naming it internally. Flagfox is in the very long list of the affected. Someone from Mozilla even linked to one of their forums on Twitter and Mozilla’s server was overloaded, so yeah… they’ve got some problems at the moment.
The only thing I can think of to attempt to work around things on my end would be to rush out an update just to resign, in the hopes that they have a new cert online and it’s just old versions that have expired. However, I don’t actually know if that’d help, and due to the sheer scale of the breakage here, I think it’s best I touch nothing for the moment. Everyone’s affected, so Mozilla is going to have to come up with a fix for everyone, one way or another, hopefully ASAP.
Mozilla released another pair of updates, now Firefox 66.0.5 and 60.6.3 (ESR), which should fix things more reliably. Apparently some antivirus programs could break things (as they often do) and very old master passwords could cause issues. In any case, it’s fixed again, for realzies this time.