How to Fix Firefox Extensions That Are Not Working

Quick Fix

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Mozilla Firefox is one of the most popular and most stable browsers out there today. It is available for macOS, Windows, and other major operating systems. It also has an Android version that is available for mobile devices.

Firefox is packed with a suite of features and a whole array of extensions, called add-ons, to improve browsing experience among users. These extensions make the users’ work lighter and easier. To install extensions for Firefox, simply go to Mozilla’s add-on page and download what you need.

Firefox extensions are mostly stable, except for some occasional glitches that are easily fixed by the developers. But the Mozilla community went into an uproar on May 3 because the Firefox browser extensions were not working. Some users saw an alert that says:

One or more installed add-ons cannot be verified and have been disabled. Learn More.

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But for some users, there was no error message or notification about the issue so they were only able to figure out that there was something wrong with the browser when they noticed that the extensions were not working.

According to Mozilla’s bug tracker, the Firefox extensions stopped working because Mozilla failed to renew a security certificate.

Mozilla Product Lead Kev Needham has acknowledged the issue and said that they are working on a fix to immediately restore the add-on functionality to Firefox.

What to Do When Firefox Extensions Are Not Working

Ever since the Firefox extensions were disabled on May 3, Mozilla was quick to the rescue and has been working on a solution to get the extensions working again. So while waiting for the patch to roll out, here are some workarounds you can try if your Firefox extensions are broken.

Fix #1: Disable Signatures for Add-ons.

The first fix requires editing the Firefox configurations to disable signatures for extensions or add-ons. Mozilla requires extensions to be digitally signed for security purposes. However, the certificate Mozilla uses for these digital signatures has expired, disabling most extensions that Firefox considers to be unsafe.

This method will disable this security feature in the hopes of restoring the functionality of the extensions. Take note, however, that this fix only works for Firefox Developer or Nightly Build.

To do this:

  1. Launch Firefox and type about:config in the address bar.
  2. Look for signatures.required and set the value to False.
  3. Close Firefox, then relaunch it to see if the extensions are not working.

This fix, though, does not work for all users and carries some risk as some malicious software could use it as a backdoor to infect your computer. So once Firefox rolls out the security patch, make sure to turn this feature on to protect your computer.

Fix #2: Enable Studies on Firefox

Mozilla has rolled out a few updates to try and fix the Firefox browser extensions which are not working. The first update was released the day after the add-on crisis, and it uses the browser’s Studies tool. This feature is used for testing new features on Firefox.

According to Mozilla, the update will be automatically installed in the background as long the Studies is enabled on your browser. To check if you have this feature switched on:

  1. Launch Firefox and click Preferences.
  2. Click Privacy & Security, then tick off Allow Firefox to install and run studies if the option is not yet enabled.

You can disable the Studies feature once the permanent fix has been applied and your extensions have been re-enabled.

This first update, however, does not work for Firefox on Android and the Firefox Extended Support Release (ESR) version. Some users also reported not receiving the update even though they have Studies enabled.

Mozilla released a follow-up update on May 5 to cover more users (66.0.4 for Desktop and Android and 60.6.2 for ESR) and another one on May 7 (Firefox 66.0.5), but there are still some who have not been able to get any updates at all.

Other Tips When Firefox Extensions Are Broken

Firefox and its extensions seem pretty stable most of the time, and incidents like this happen rarely. The last time the scenario occurred was three years ago when add-ons failed to install due to the invalid signature error. Fortunately, Mozilla quickly released a patch to resolve the issue.

When your Firefox add-ons are misbehaving and there is no major issue that should affect the browser’s performance, you can try the general fixes below.

Tip #1: Restart Firefox.

If your problem is caused by a temporary system glitch, restarting your browser will do the trick. To reboot your browser:

  1. Choose File from the Firefox menu bar.
  2. Click Quit.
  3. Restart your computer and open Firefox again.

This simple troubleshooting method usually resolves most minor Firefox issues.

Tip #2: Create a New Profile.

A corrupt profile can cause various Firefox problems, including broken extensions. If this is the case, creating a new profile might resolve the issue. You can copy your passwords, bookmarks, and other data to your new profile so you don’t have to worry about starting from scratch.

Follow the instructions below to create a new Firefox profile:

  1. Close the browser completely by selecting Quit from the Firefox menu.
  2. Open the Profile Manager by typing this command in the Terminal: firefox -ProfileManager -no-remote.
  3. Click Create Profile to start the profile wizard.
  4. Hit Next, then type in the name of your new profile.
  5. Click Finish.
  6. Choose your new profile in the Profile Manager, then click Start Firefox to begin using that profile.

Download a few extensions to check if they are working on the new profile before transferring your data over.

Tip #3: Clear Browser Cookies and Cache.

Many Firefox and add-on problems can be fixed by clearing your browser’s cookies and cache. To do this:

  1. Click Tools from the Firefox menu, then select Clear Recent History. This will bring up the Clear Recent History window.
  2. Choose Everything under the Time range dropdown menu.
  3. Click Details, then tick off Cache and Cookies from the list of items to clear.
  4. Hit the Clear Now button.
  5. Close Firefox.
  6. Clear Flash cookies by typing this command in the Terminal: find ~/.macromedia/ -type f -name \*.sol -exec rm ‘{}’ \;

Check Firefox again if you’re still experiencing issues with your add-ons.

Tip #4: Clear Junk Files.

Accumulated junk files can consume resources and potentially affect system performance. For thorough cleanup, you might consider using a tool like Outbyte macAries for Windows or Outbyte macAries for Macs. Ensure the tool is compatible with your needs before using it.


Firefox add-ons allow users to personalize their browser and improve browsing experience. But incidents like the recent one that left most extensions broken can be extremely annoying, especially if you are using Firefox as your main browser. If you’ve been affected by this issue, you can try the workarounds above to resolve it. You can also try the tips if you’re experiencing an isolated problem with extensions.

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