As explained in bug 718255, nsIPrefBranch2 has been merged into nsIPrefBranch. nsIPrefBranch2 will continue to work as a proxy, so no breakage should occur. We need to flag all instances of this interface calls and show a warning. This is a compatibility warning, so the add-on should still be upgraded in this case. Message: The nsIPrefBranch2 interface has been merged into the nsIPrefBranch interface in Firefox 13. Once you drop support for older versions of Firefox, you should stop using nsIPrefBranch2. You can use the == operator as an alternative. See <LINK> for more information. Link: https://developer.mozilla.org/en/XPCOM_Interface_Reference/nsIPrefBranch2 Affected add-on: https://addons.mozilla.org/en-US/firefox/addon/download-statusbar/ (and most others).
verified fixed at https://addons-dev.allizom.org/en-US/developers/upload/d8524b159a744d20bcc5d6ab5b1f8623