Purpose

This lets you modify your local Firefox installation so that you can use a standard release channel Firefox, but still install unsigned addons.

You probably only want to do this if you are a developer of add-ons (for example, of your own personal addons you want to run locally but not share with Mozilla for signing).

About unsigned addon support

The standard release channel builds of Firefox now have a setting built into them that means that all addons must be signed by Mozilla, and this setting cannot be changed by simple means (including through settings in about:config).

Firefox Developer Edition doesn't have this limitation. You can install unsigned extensions by downloading Firefox Developer Edition and then toggle xpinstall.signatures.required to false in about:config. The Developer Edition is effectively a beta release channel, and is updated nightly.

For various reasons, you might prefer to be on the more stable release channel. If you want that, but to also install unsigned addons, the scripts provided here are what you need.

Prerequisites

The scripts use bash, Info-ZIP zip and unzip, mktemp (from GNU coreutils), and sed. Ensure you have these installed before using the script.

Patching

Follow the following steps to patch Firefox to disable addon signing.

1. Update Firefox to the latest version before starting, to save extra steps to update later.
2. Configure Firefox not to auto-update using about:preferences#general, because you will now have additional manual steps to update (see the Updating section).
3. Find the directory where you have installed Firefox. This is the path where the firefox binary resides (excluding the name of the binary - so it is the path to the directory and not the binary).
4. Run export MOZILLA_HOME=/path/to/firefox, substituting the directory in place of /path/to/firefox.
5. Ensure that you have exited from Firefox.
6. Run the patch-firefox.sh script. If it works, the last line should be Done.
7. If you have an existing Firefox profile, you will also need to find your profile directory. The location depends on your configuration, but on Linux is usually a subdirectory of ~/.mozilla/firefox/, called xxxxxxxx.default, where xxxxxxxx is replaced with a random string of characters.
8. In that profile directory (if you have one already), you will need to delete the subdirectory called startupCache.
9. Start Firefox.
10. Navigate to about:config.
11. While on about:config, go to the Developer tools (F12 by default), and switch to the Console tab. Type in ChromeUtils.import("resource://gre/modules/AppConstants.jsm").AppConstants.MOZ_REQUIRE_SIGNING. If you see false, the patching has worked. If you see true, something has not worked. If it did not work, ensure you have run the patch-firefox.sh script with the correct MOZILLA_HOME, and that you have successfully deleted the startupCache before starting Firefox, and try again.
12. In about:config, search for xpinstall.signatures.required, and change the value to false if it is true.
13. Copy your extension into the extensions subdirectory of your Firefox profile directory.
14. Restart Firefox. Firefox will prompt to confirm that you want to enable the addon.

Upgrading Firefox

You should continue to upgrade Firefox whenever it prompts you to upgrade it to ensure you have the latest security patches. However, before applying upgrades, you should:

1. Exit from Firefox.
2. Ensure you have exported MOZILLA_HOME (per the steps for patching)
3. Run unpatch-firefox.sh
4. Start Firefox using the -ProfileManager option, and start it using a different profile - create a new one if necessary (don't start it with your normal profile as this will disable all your unsigned addons, and you will need to clear caches again).
5. Apply the update.
6. Run patch-firefox.sh
7. Start Firefox again using your default profile.