If your Firefox browser add-ons have suddenly stopped working, are now “unsupported” without any warning, or you can’t install any new ones, don’t worry: Mozilla is aware of these bugs and is working on fixing the issue. Resist the urge to adopt any clever workarounds right now, which might mess up any solutions Mozilla is trying to implement.
According to Mozilla’s blog post:
Late on Friday May 3rd, we became aware of an issue with Firefox that prevented existing and new add-ons from running or being installed. We are very sorry for the inconvenience caused to people who use Firefox.
Our team identified and rolled-out a temporary fix for all Firefox Desktop users on Release, Beta and Nightly. The fix will be automatically applied in the background within 24 hours. No active steps need to be taken to make add-ons work again. In particular, please do not delete and/or re-install any add-ons as an attempt to fix the issue. Deleting an add-on removes any data associated with it, where disabling and re-enabling does not.
In other words, the best way to resolve these recent add-on issues is to keep Firefox updated to the most recent version—don’t do anything else. Mozilla’s fixes are implemented in versions 66.0.4 of Firefox, on Desktop and Android, and 60.6.2 for Extended Support Release (ESR).
It’s possible your browser may have already updated to the newest version if you have auto-updates enabled; if not, here’s how to check for a new version of Firefox:
Depending on your platform and device, you can find your browser’s version number by opening Firefox then going to Help & About Firefox, or Firefox & About Firefox.
In both cases, a new window will pop up. The version number is displayed under the Firefox logo. This window will also alert you if any updates are available.
You can also download the latest desktop versions from the Firefox download page.
Android and iOS
Simply pull up your platform’s app store and see if any updates are available — much as you would any regular app. (If you’re on the latter, you can’t even install add-ons, making this issue moot.)
If you’re not on the right version of Firefox, but no updates are available, that means the hotfix probably hasn’t rolled out to you yet. Mozilla’s blog post says all users should have it by the end of the day Monday, May 6, but this is only an estimate.
It’s also important to note that these hotfixes, while helpful, are short-term solutions while Mozilla works on a permanent fix. In other words, you might continue to encounter bugs with your add-ons even after updating to the browser’s latest version.
For instance, some extensions may incorrectly appear as unsupported in the 60.6.2 version of Firefox ESR, but according to its patch notes, users should still be able to reinstall and reconfigure them. A small number of add-ons and browser themes may remain unusable even after applying the update.
Even with these lingering errors, it’s wise to wait for Mozilla’s official solution—whether it’s more hotfixes or a more thorough bug squash—rather than attempt to solve the issue with workarounds that could wind up backfiring.