The latest update to Firefox (41.0b1) aggressively blocks the installation of unverified extensions, namely HTTPS Everywhere and Privacy Badger.

How might I be able to force these extensions to install? Is there a setting inside about:config I could temporarily toggle?

Mozilla highlights this change to Firefox here, noting its previous efforts to be inefficient at corralling malicious extensions.


Yes, there is a setting in About:config, its name is xpinstall.signatures.required. Double-click on the preference name so that its value is set to false. Now you can install unsigned extensions in Firefox. A browser restart is not needed.

  • 2
    Fantastic! This fix will suffice until EFF and others have there extensions verified. – VitaminYes Aug 12 '15 at 21:02
  • 1
    This also won't work after version 43+. :( – ꜱᴜʀᴇꜱʜ ᴀᴛᴛᴀ Aug 6 '16 at 19:47
  • Despite many sources saying it won't work in recent FF, it worked for me in 48.0 on Linux. I had to open the addons page and drag the xpi file there. – That Brazilian Guy Aug 9 '16 at 13:51
  • @ThatBrazilianGato: is is not working for me on Win7 FF48.0 :( – glavić Aug 16 '16 at 13:37
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    That's it for me. Bye Firefox, loved you since version 0.6. :-( Hope there will be a workaround some day. – andreas Aug 30 '16 at 21:59

On Firefox 48 and above, this method doesn't work. Instead you should create two config files inside Firefox directory.

  1. Create config.js file in notepad (make sure file extension is .js and not .txt):

    try {
    Components.utils.import("resource://gre/modules/addons/XPIProvider.jsm", {})
    catch(ex) {}
  2. Move config.js to your Firefox installation directory:

    Windows: C:\Program Files\Mozilla Firefox
    (or C:\Program Files (x86)\Mozilla Firefox )

    Linux: /usr/lib64/firefox-< version >
    (or /usr/lib/firefox-< version > )

    Mac: /Applications/Firefox.app

  3. Create config-prefs.js in notepad:

    pref("general.config.obscure_value", 0);
    pref("general.config.filename", "config.js");
  4. Move config-prefs.js into Firefox defaults\pref directory.
    (e.g. C:\Program Files\Mozilla Firefox\defaults\pref)

  5. Restart Firefox.

  6. Drag the unsigned XPI into Firefox window, or use the "Install Add-on From File" option, in the settings of Firefox Add-ons.

Originate from this source: https://forum.mozilla-russia.org/viewtopic.php?id=70326

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