Add-on Compatibility for Firefox 10


Firefox 10 was pushed to the Aurora channel a few weeks ago, so it’s time again to round up all bugs that could be breaking add-on compatibility. It’s a pretty long list this time, but most are removals of obscure and rarely-used XPCOM and DOM interfaces.

As usual, you should check Firefox 10 for Developers for additional information.

DOM Changes

XPCOM Changes

Other Changes

New stuff!

Please let me know in the comments if there’s anything missing or incorrect on these lists. If your add-on breaks on Firefox 10, I’d like to know.

The compatibility bump to Firefox 10 will happen very soon. If you want your add-on to qualify for this, it should be compatible with 9.*. Versions awaiting review also qualify.

Tags: , , ,

Categories: compatibility, developers, documentation

12 responses

  1. Lozzy

    Are these changes being made in preparation for Addons Compatible By Default? I figure that old cruft is being removed now so that it won’t cause more of an issue further down the line.

    1. Jorge Villalobos Author

      They’re made independently. Compatible by default is being worked on as we speak, and we will be talking more about this in the future.

  2. Gyula

    már lassan egy hónapja azt írja nekem hogy össze omlott a Firefox

  3. Dory Zidon

    And also what happens if I load a new version into AMO while I’m in queue for a full review for example?
    Would my place in the queue stay the same but I will get you guys to review the latest version always?


    1. Jorge Villalobos Author

      We only review the latest version. If you upload a new one while you are waiting in the queue, the one that was previously waiting for review will be disabled. The new one will be pushed back to the end of the queue, unfortunately. That’s a know bug and it has been reported.

  4. Flepo

    i’ve one question regarding switching from PRBool to bool:

    Did i have to change this line of code in my addon working with ff10?

    aSubject.QueryInterface(Components.interfaces.nsISupportsPRBool).data = true;


    Many Thanks and Regards,

    1. Flepo

      next uncertainty is:

      var cancelQuit = [";1"].createInstance(Ci.nsISupportsPRBool);

      Any recommendations to change this?


      1. Jorge Villalobos Author

        It looks like nsISupportsPRBool is still there, and being heavily used in Mozilla code, so you’re OK to continue using it that way.

        1. Flepo

          Many Thanks Jorge, it’s a pleasure,

  5. Max Fenton

    Hey Jorge,

    Any idea why Readability is showing up as incompatible with Firefox 10 for Windows? The same exact addon works when installed from

    Any help would be appreciated. You can tweet @readability or reach me directly if you have any time at all to spare.


    Max Fenton
    Readability Community Support

  6. Darlene

    TypeError: xulItems[item].getAttribute is not a function appears every time I open my FireFox. I have removed the program and reloaded it and that didn’t remove it. Help!

    1. Jorge Villalobos Author

      Try starting Firefox in Safe Mode. That sounds like one of your add-ons is broken, so you can try disabling or removing some until the problem is fixed. If you determine which add-on is causing the problem, let us know.