Disable add-on signature enforcement in Firefox 49 and above

Starting with Firefox 48, Mozilla made the add-on signature enforcement mandatory. The user cannot disable it using the about:config flag or using any other method. Here is a hack which will allow you to bypass the requirement and install unsigned addons in the browser.


While Firefox now comes without the option to use unsigned addons, there are a number of ways to bypass the add-on signature requirement. One of them involves a system script that defines which browser objects should request the digital signature. If you modify the script, it will be possible to install add-ons. Follow the instructions below.

Disable add-on signature enforcement in Firefox 49 and above

  1. Open Notepad and paste the following text:
       try {
       Components.utils.import("resource://gre/modules/addons/XPIProvider.jsm", {})
       catch(ex) {}


  2. Save your file under the name "config.js". I suggest you to include the file name in quotes in Notepad's Save dialog as shown in the screenshot below. Otherwise, Notepad may append a ".txt" extension to the file name, making it "config.js.txt".
  3. Now, copy or move the config.js file you created to the following location.
    In Linux 32-bit:

    In Linux 64-bit:


    In Windows 32-bit:

    C:\Program Files\Mozilla Firefox

    In Windows 64-bit

    C:\Program Files (x86)\Mozilla Firefox



  4. Create a new text file again in Notepad with the following content:
    pref("general.config.obscure_value", 0);
    pref("general.config.filename", "config.js");


  5. Save the text above to a file named config-prefs.js.firefox-save-config-prefs-js
  6. Run Firefox and open Help -> Troubleshooting Information. The following page will be opened:firefox-open-help-troubleshootingfirefox-troubleshooting-page
  7. Scroll down to the line "Profile folder" and click the "Show folder" button on the right. The folder will be opened in File Explorer.firefox-opened-profile-folder
  8. Copy or move the config-prefs.js file you have created to this folder:firefox-put-config-prefs-js-in-the-profile
  9. Restart Firefox.
  10. If it does not work, try to put the file config-prefs.js in the folder
    C:\Program Files\Mozilla Firefox\defaults\pref

    Then restart the browser. Thanks to our reader Macgryver for this tip.

That's it. After you put the required files to the locations mentioned above, Firefox won't require digital signatures for add-ons. The first script is a configuration file which clears the SIGNED_TYPES array, which points the browser to identify add-ons as objects that require signing. The second file activates the first script.
To undo the changes you made, just delete these two files and restart the browser. Thanks to OpenNews for sharing this tip.

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Author: Sergey Tkachenko

Sergey Tkachenko is a software developer who started Winaero back in 2011. On this blog, Sergey is writing about everything connected to Microsoft, Windows and popular software. Follow him on Telegram, Twitter, and YouTube.

16 thoughts on “Disable add-on signature enforcement in Firefox 49 and above”

  1. Very sorry, but on Mozilla Firefox 49.0.1 it didn’t work… At least to install uBlock Origin RC1 either through the browser or via installation from a file by specifying the directory of the downloaded file…

      1. Initially after following the above instructions, it did NOT work. Then I toggle xpinstall.signatures.required
        then restart and toggle it again then restart … and suddenly it works.

        Today when I started firefox (Linux Mint), I noticed that it did NOT work again.

        Maybe somebody knows an alternative solution. Thanks.

  2. Here’s a solution…
    You to put the file config-prefs.js to
    C:\Program Files\Mozilla Firefox\defaults\pref or
    C:\Program Files (x86)\Mozilla Firefox\defaults\pref
    or for custom installation directory\defaults\pref

  3. I’t didnt work on any configuration suggested. I should stick to FF 46, the last version that after tweaking allowed my old friend extentions to work

  4. Doesn’t work with 51, they disabled processes.

    Beyond Firefox 50, we have more work to do to enable multi-process Firefox for users with as yet unsupported extensions. In Firefox 51, if all testing goes according to plan, we’ll be enabling multi-process Firefox for users with extensions that are not explicitly marked as incompatible with multi-process Firefox.

  5. A correction to step 3 above: C:\Program Files (x86)\Mozilla Firefox is for the 32-bit version of windows.
    C:\Program Files\Mozilla Firefox is for the 64-bit version of windows.

  6. I would like to update my (very) outdated version of Firefox (currently on version 70) to the latest version. If I do that, will all of my extensions be disabled again?

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