Add-on Compatibility for Firefox 42

Firefox 42 will be released on November 3rd. Here’s the list of changes that went into this version that can affect add-on compatibility. There is more information available in Firefox 42 for Developers, so you should also give it a look.



  • Split nsIContentPolicy::TYPE_SUBDOCUMENT into TYPE_FRAME and TYPE_IFRAME. This should only affect your add-on if it implements nsIContentPolicy.
  • Use origin for nsIPermissionManager. Permissions in the Permission Manager used to be handled per-host, and now they will be handled per-origin. This means that and have different permission entries. This changes some methods in the Permission Manager so they accept URIs instead of strings.
  • Update: nsINetUtil.parseContentType has been renamed to parseResponseContentType as part of a security fix. Its behavior should remain the same.


Please let me know in the comments if there’s anything missing or incorrect on these lists. If your add-on breaks on Firefox 42, I’d like to know.

The automatic compatibility validation and upgrade for add-ons on AMO will happen in the coming weeks, so keep an eye on your email if you have an add-on listed on our site with its compatibility set to Firefox 41.

4 responses

  1. Kohei Yoshino wrote on :

    Japanese translation is up!

    1. Jorge Villalobos wrote on :


  2. Vitaly Zdanevich wrote on :

    I can’t send email to you:

    550 5.1.1 : Recipient address rejected: User unknown in virtual alias table

    1. Jorge Villalobos wrote on :

      My address is jorge AT mozilla DOT com. It should work since I’m getting tons of email 🙂