Firefox add-ons cannot be verified and have been disabled

Posted on May 5, 2019 at 5:07 pm

On May 4 2019 the web browser Mozilla Firefox started to show a warning message “One or more installed add-ons cannot be verified and have been disabled” and all installed browser extensions were all disabled. This created some panic within Firefox users and myself too, as I found all my Firefox extensions disabled without an option to re-enable them.

A workaround that works

Mozilla is working on a fix and should release a new Firefox version hopefully in a few hours. Meanwhile, there are a few possible workarounds that may work for Firefox users.

Here is a workaround I have tested and seems to work fine:

1 – Close Firefox process (firefox.exe)

2 – Browse to the Firefox profile folder:


Replace PCUSER with your PC username and xxxxxxxx with your Firefox profile.

3 – Edit the file extensions.json with Notepad++ or Notepad

4 – Replace all instances of “appDisabled”:true with “appDisabled”:false

5 – Replace all instances of “signedState”:-1 to “signedState”:2

6 – Save the file and start Firefox

7 – Disable and re-enable all extensions in about:addons

The real solution

You will of course need to update to a newer version of Firefox when available.

You can follow Firefox releases here:

Mozilla Firefox Release Notes

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