Firefox 33.1 compatibility

As part of yesterday’s Firefox 10th anniversary celebrations, we released a new special version of Firefox, version 33.1. Since it was meant to be a surprise release, it didn’t ride the trains in the same way as other features and it ended up unexpectedly breaking things for some add-ons.

The new Forget button

There’s a new button in the toolbar palette. It doesn’t appear in the toolbar by default, but you can see it if you enter customization mode. Unexpected buttons can break complete themes and this case is no exception. The solution is to update the theme to support this new button.

Binary XPCOM and version numbers

Binary XPCOM is a legacy technology that we hope to phase out of add-ons soon, in favor of JS ctypes and other pure JS solutions. Current support for binary XPCOM in add-ons is clunky at best, and developers need to rebuild their components for every new major version of Firefox.

After the 33.1 release, we discovered some add-ons doing this in their chrome.manifest files:

interfaces components/component33.xpt appversion=33.0 appversion=33.0.1 appversion=33.0.2 appversion=33.0.3 ...

This allows developers to have components built for various Firefox versions in the same add-on package, and declare which components need to be loaded for which Firefox version. However, since this doesn’t contemplate 33.1, no components are being loaded for that version. The easier solution in this case is just to add 33.1 to that list (33.1 is binary-compatible with the regular 33 branch). I’m fairly sure we won’t have any more surprise releases before we discontinue binary XPCOM, so I don’t think a more robust solution is needed. Update: however, please note there’s already a 31.1.1 and there could be other 31.1.* updates.


I’m sorry for the last-minute inconvenience, but hopefully the fixes are easy enough that you can issue quick updates for your add-ons and most of your users aren’t affected. If your add-on is on AMO, feel free to contact us to the amo-editors list or me directly so we can prioritize your compatibility updates.

34 comments on “Firefox 33.1 compatibility”

  1. Emil wrote on

    I’m from Bulgaria
    after the update I don’t have Forget button in all my Firefox browser. I checked in other comuters – the same.

    1. Jorge Villalobos wrote on

      You don’t see in the toolbar customization dialog? It shouldn’t appear in the toolbar by default.

  2. Emil wrote on

    When I open Customize there is no such button to drag. No new button at all the same situation on all six Firefox browsers in my office.

    1. Jorge Villalobos wrote on

      It should show up if you have 33.1 installed. If it doesn’t, try looking in

  3. Kohei Yoshino wrote on

    Japanese translation: 🙂

    1. Jorge Villalobos wrote on


  4. Emil wrote on

    From three new features only Duck Duck Go Search is availabale. Very strange. I know that the button don’t appear on the toolbar by default but it is not available in Customize dialog window – only standart other buttons

    1. Jivko wrote on

      Емо, ползваш ли някаква тема или добавки?

    2. Hector Zhao wrote on

      Hi Emil,

      Enhanced Tiles and forget button are only available in selected locales, guess this is also “surpurise” for some localizers.

      1. Emil wrote on

        Thank you,
        but that must be announced to everyone, not to force people to reinstall their browsers or reset them. Very unpleasant surprise really.

  5. Bob wrote on

    When I brought up Firefox, the update began and 33.1 installed itself. The instructions for the ‘forget me’ key also appeared, and I had to accept it for the key to install too.
    Others may have been too quick on enabling the install? Is there a way to set it after you’ve declined it??

  6. P.S. wrote on

    For example, just compare a Firefox 33.1 version With a NL (Dutch) version and you will see that the ‘Forget’ button (which should have the name ‘Vergeet’ in Dutch) it is actually not there at all.

    Feedback; Please consider to change the colours of your Forget pane/window from red to green, privacy is something positive and a green pop up window (#) is visually less agressive.

    (#) ‘Pop up window-menu’, why?
    We have already the settings available in the history menu.
    Please even consider to make it a fast ‘one-click button’, no pop up’s (we don’t like them), just a simple and fast erase.

    The solution now is a ‘solution in between’ , still an extra window but not with all the options, also not really faster because it’s just a one click difference (from three to two), while the history menu has better options with three clicks.
    The faster the button is, the more it will be used (probably).

  7. Bhagat wrote on

    33.1 is showing increased CPU usage.

    I did update all the addons and the increase CPU usage continues.

    1. Jeff N wrote on

      I have same problem

  8. Massive wrote on

    Guys, cpu usage shoots to 100% on older machines for some websites (eg, trello). You can’t do suprise releases, break stuff, and expect to be considered a production browser, common.

    And i can’t roll back?

  9. reqq wrote on

    I think i had enough. Everytime i updated Firefox (last 5-10 updates) my interface is a complete mess. And im talking about the basic button position and functions these have. 33.1 is even worse. Now the “plus” button that was a shortcut for alot of functions ONLY adds a new tab. I had to manually add the old ugly menu row to even get to my addons.
    Now i cant move by reload button or back/forth button either. It makes zero sense to spread out buttons, it make it sluggish to use and you have to move your mouse longer. Might not seem to be a big deal, but in the long run, if every program used this simple solution you will get less mousearm strain and you will be more effictive.

    I just dont get it. Why is this happening? Why cant you just have one simple design that let users move whatever button they want and LEAVE IT THERE. Dont become another APPLE that think they know the ultimate interface design. Because let me tell you something, there is no such thing. Becuase it is 100% subsective.

    Let users move around every button and tab location they want. Have one “startmenu” button in the corner that is a shortcut to everything. And make sure that this simple thing is always working when you update the engine.

  10. Geo wrote on

    I’ve lost many important add-ons and can’t even get them back! Examples: Web Developer 1.2.5, SEO Toolbar 1.2.10, also some extension that showed me the IP of the page I’m on that I forgot the name of (cause I installed it like 4 years ago). All gone without a trace! Deleting extensions.ini etc. didn’t help. I had to install them anew and even then they won’t work! They now show up as installed extensions but they are not working at all and they don’t appear in the drop-down from the Menu Bar.

    First time anything like that happens to me. Lost more than an hour already trying to fix this to no avail. Highly disappointed.

    1. Jorge Villalobos wrote on

      Which version of Firefox are you using?

  11. coyote wrote on

    33.1 uninstalled my JS Switch 0.2.10 and Clear Console 1.11 add-ons. I appreciate that your “forget button” does something similar to Clear Console, but it’s not quite the same.

    I run both of these add-ons for good reasons, and trust them.

    I am curious about what good reasons Mozilla thinks it has for scramming them with no notice? And doing it again after I re-installed ’em?

    1. Jorge Villalobos wrote on

      The update shouldn’t remove any add-ons, regardless of what they do. There is a known problem if you were using the Aurora channel and then you migrated to using the new Firefox Developer Edition. For some cases, a new profile is created and your data and add-ons appear to be gone, but it’s only a matter of using your old profile. Is that your case?

      1. Thomas wrote on

        I have the same problem with some addons that just keep being removed after I restarted the computer.
        I honestly have no idea what you mean with aurora and a new profile that might be created. I just used it normal way all the time. Don´t even have a syncaccount. And I´m using the normal version 33.1.1 not a Firefox Developer Edition.
        Help respectively fixing the problem would be great. Because it´s super annoying to reinstall 3 tabs everytime you started your computer. Thanks.

  12. LaneyB wrote on

    33.1 hangs and the only way to end the process is to go into the application area of task manager then i see it says i’m running 32 what gives with this?

    1. Jorge Villalobos wrote on

      Please visit our support site for help.

      1. Howard wrote on

        After downloading this version, by coincidence or not, most pages do not load fast at all. They keep on turning and turning. Tried every fix and known remedy, reinstalled twice. As it happens, before this I had an At and T upgrade speed service and ever since then, the new version seems to be like this. Pictures load and dont load from internet. Youtube is worse than ever before…… Gmail I must virtually hit the key to get it to load within 8 seconds….then only to stiop in between. ????? SO,,,, still do not know if it is Firefox or my ISP that is giving me the problem.

  13. Bjorg Jenson wrote on


    OH MY!

    I installed the latest update to my firefox, now at 33.1, and when I restarted, 90% of my addons are gone!!!
    One or two are left, all my bookmarks are there, but all the rest, gone, not even in the addons list…..

    I had some addons for a very long time, for example ABP and a cookies addon, which I manually added sites to the exceptions list over the yearsm and now all gone, I have to start again????

    Seriously bad update if it cant tbe recovered….

  14. Deejay wrote on

    after update i cant open FF at all so sad i cant do anything at all …. i have install and uninstal many times

  15. Greg Gillespie wrote on

    I’m the same as Bjorg Jensen – 90% of my updates are gone including a noscript that I’ve carefully cultivated for several years! 🙁

  16. mark wrote on

    I can’t start FF either. I guess I have to find the old version and re-do the whole shooting match again. I just did the update about 15 minutes ago. why has it been left running all this time with all these know issues.

  17. Bjorg Jenson wrote on

    After more searching. it had nothing to do with firefox apparently.

    It was an update by AVAST , that caused firefox addons to disappear.

    Sorry about that mozilla 🙂

    On the bright side, I re-installed the addons, and the previous info/data/setting for each addon was as it was previously!

  18. Geneaux wrote on

    I’m running 33.1.1 which I updated from 33.1 recently. I’m encountering an issue with the forget button in which the graphical icon itself does not appear. The button itself is there but the icon meant for GUI purposes does not show. For example, if I were to place the button in the toolbar, visually it’d look like blank space.

    Is there a sort of installation repair option with Firefox? Or should I just proceed with a re-installation? I’ll likely try the latter before I jump to any conclusions.

    1. Jorge Villalobos wrote on

      You can find help on our support site. Reinstalling won’t help, but maybe resetting the profile will.

  19. Columbus wrote on

    It also broke lastpass. It does not install in English. It installs in some other language. And does ot have option to switch back to English. It had to be uninstalled. Hope a fix can be found soon.

  20. Rob wrote on

    I have been a loyal fan of Firefox, but it has been crashing more and more and not working as it should. Now you do a “surprise” update? Are you nuts? I am in my busy season and all of a sudden Lastpass doesn’t work?!!! Why are you forcing me to Chrome? 🙁

  21. Kiki wrote on

    Hello, i have some problem with new mozilla v 33.1… how can i block help menu in new open menu pallete??
    because it always used by my workers to erase all add on ive installed, by go to help menu, then click troubleshouting information, and click on reset firefox..then u can get new mozilla firefox without any addons i already installed earlier..Can u please give me some advice, so i can block my workers to access help menu??
    thanks alot