Disable Extension Signing in Nightly and Developer Builds

Mozilla has allowed extension signing not to be enforced on the Nightly and Developer Edition (Aurora) builds for add-on developers. However, it is enabled by default though when you install or update to these builds. To turn off the extension signing follow these steps:

  1. In a new tab type: about:config in Firefox’s address bar and hit enter.
  2. Confirm you will be careful if a warning message is displayed.
  3. Search for xpinstall.signatures.required.
  4. Double-click on the preference name so that its value is set to false.
  5. Restart the browser to reactivate any disabled extensions

The release version of Firefox 41 (September 2015) will still have this option (or something similar) so users can still install/use unsigned/unverified extensions. However, starting with the release version of Firefox 42 (November 2015) unsigned/unverified extensions can not be installed/used.

Note: This does not apply to Firefox ESR until version 45 (March 2016). Also, this does not apply to Pale Moon or any other unbranded releases of Firefox.

via ghacks.net