Update:
Mozilla has release an update, yesterday, that fixes the problem for about half the users.
In the preferences tab, you can scroll down to privacy and opt in to studies. You may or may not have the study available
The hotfix is #1548973
If you do not have the ‘study’ hotfix available there is a well duplicated alternative I will not link to directly.
Mozilla, by licensing requirement, has posted the XPI to the various code repositories.
Download the xpi, load up Firefox, then drag-n-drop the Xpi into Firefox.
You’ll see most of your extensions come back immediately. Restart Firefox for the rest to reload.
Code:
install at your own discretion
I’m not posting the direct link for two reasons. First Mozilla is attacking any size that posts the link; because:
Second, Mozilla claims this will potentially break any permanent solution they come up with.
Looking at the code and what it does, it simply disables the clock check on current and previous signed extension certificates. Not new ones. There is a potential security issue here. However personally, I feel the loss of security extensions outweighs the risks.
Make your own decisions though based on your use.