Firefox 3.6 was released on Jan 21st and has already been downloaded more than 35 million times! It features a faster JavaScript engine, faster DOM performance and a bunch of new HTML5 features. Highlights for web developers include support for the WOFF font format, new CSS features like gradients and multiple backgrounds, drag and drop, File API, device orientation, and more. Want to see the full list? Look at our Firefox 3.6 for Developers page on developer.mozilla.org.

We hope that you took the time to test Firefox 3.6 on your web sites before the release. If you didn’t, it’s not too late to let us know about issues. Here are a few problems that we’ve seen in the wild so far:

  • We’ve seen a couple of issues with the FCKEditor component, used widely on the web. It apparently doesn’t handle dates after 2009 properly (this is the first major browser release in 2010, a new decade!) and it also has some problems with document.readyState.
  • People who had the YSlow extension installed saw crashes with Firefox 3.6. YSlow has been updated to version 2.0.6 to fix the issue
  • Some Facebook apps were broken by a change we made to comply with the upcoming HTML5 standard. We updated element.getElementsByTagNameNS and document.getElementsByTagNameNS to no longer case-fold when doing tag name lookups. (We strongly suggest that you only use lower-case for tag names for many reasons, including this.) For more information, please see this note from Henri Sivonen about what’s changed. Facebook has since fixed the issue in their code, but other sites may also be tripping over this.

We’re looking for feedback on any developer-facing regressions you’ve seen in 3.6 from 3.5. Please comment on this post if you have feedback.

76 comments

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  1. Brian wrote on February 4th, 2010 at 9:47 pm:

    Not so much of a functional regression.
    However, I am not too fond of the new tab behavior. Previously a new tab would open after all existing tabs. Now it opens next to the window in which it was opened. Can this be configured? Do you know the bug# that changed this behavior? Thanks.

    Reply

  2. Michael Kaply wrote on February 4th, 2010 at 9:56 pm:

    I know of at least two issues.

    1. On this site:

    http://areyouwatchingthis.com/login

    The Login text appears twice. It only appeared once on Firefox 3.5. Still investigating why.

    2. Flash is horribly broken when displayed in the sidebar. This is a major regression.

    Reply

  3. boye wrote on February 5th, 2010 at 12:30 am:

    I am getting the following error repeatedly when typing in a regular input field, afaik it’s triggered on keyup/keypress.

    [Exception... "Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getBoolPref]” nsresult: “0x8000ffff (NS_ERROR_UNEXPECTED)” location: “JS frame :: file:///C:/Program%20Files/Mozilla%20Firefox/components/nsFormAutoComplete.js :: anonymous :: line 97″ data: no] file:///C:/Program%20Files/Mozilla%20Firefox/components/nsFormAutoComplete.js Line 97

    When I set the autocomplete attribute it’s gone, so I presume it has something to do with a security setting or maybe an add-on?

    Cheers,
    Boye

    Reply

  4. Gijs wrote on February 5th, 2010 at 1:16 am:

    Note that there are other case issues related to the getElementsByTagNameNS one in 3.6 – for instance, after adoptNoding an XHTML element with (partially) uppercase attributes into an HTML document, the attributes are no longer available using getAttribute (although they can be accessed using getAttributeNS and the attributes collection). ChatZilla got bitten by this ( https://bugzilla.mozilla.org/show_bug.cgi?id=541647 ).

    Reply

  5. Jesper Kristensen wrote on February 5th, 2010 at 1:20 pm:

    bug 476856 changed handling of syntax errors in CSS urls, which broke the following site, which works in IE8, Chrome and Firefox 3.5: https://www.tinglysning.dk/

    They have “background-image: url(foo.gif’);” in their style sheet, which breaks the entire rest of the style sheet in Firefox 3.5, but only breaks the next single block in all other browsers.

    Reply

  6. Andrey M. wrote on February 5th, 2010 at 1:58 pm:

    There is black rectangle flicker while loading java applet. In FF 3.5 it’s ok.

    Reply

  7. Dwight Stegall wrote on February 6th, 2010 at 12:35 am:

    I use an animated Java Applet weather map everyday and I have seen no black rectangle during or after loading. This is a Weather.com Applet that is about 14 years old.

    I’m using version 6 Update 17 java Runtime on Windows Vista Home SP2.

    Reply

  8. AlfonsoML wrote on February 8th, 2010 at 3:51 pm:

    Your second comment about problems with FCKeditor is really a problem with another editor named KTML, seems to be an old extension for Dreamweaver.

    Reply

  9. Kristijan Jovanovic wrote on February 9th, 2010 at 4:47 am:

    With Firefox 3.6 is changed way that new tab opens. In Firefox before 3.6 new tabs were opened in the end of tab toolbar (which was perfect for me.) In Firefox 3.6 new tab opens in the tab next to active one. Please, at least put the option in “tab” submenu to choose the way for opening tabs.

    Reply

  10. darkyndy wrote on February 9th, 2010 at 4:53 am:

    I work on a site where I have input fields with 25px height (21px height+ 4px padding top). The problem occurs on FireFox 3.6 where the text is automatically vertically centered so the CSS should look like 25px height without any padding top. What I should do in this case?

    I tested on Windows and MAC with FireFox 3.5.7 and FireFox 3.6

    Reply

    1. josheat wrote on March 21st, 2010 at 10:25 pm:

      I’m getting this a lot as well, its definitely something that should be looked at.

      If I figure something out, I’ll come back and post here

      Reply

  11. Nehal wrote on February 9th, 2010 at 12:17 pm:

    I don’t know what problem i am getting in my FF 3.6 version but when i opened some of live stock quote website. mozila getting crashed and suddenly it’s closed without any warning or notice before close. these happened to me many times after upgrading from 3.0 version

    Reply

    1. darkyndy wrote on February 11th, 2010 at 6:19 am:

      This happened to me too, but I think that the main problem is the operating system (Windows 7 in my case). On Windows Vista I didn’t had any problems … but with Windows 7 there are some…

      About my problem posted above, the solution was to use for input fields only padding and no height. In this was the text is center aligned and works in all browsers.

      Reply

      1. josheat wrote on April 20th, 2010 at 4:13 pm:

        Cheers mate, appreciated!

        Reply

  12. Thomas Jacobs wrote on February 9th, 2010 at 12:57 pm:

    I am not a developer.

    I have found two problems that I could only alleviate by going back to 3.5.7

    1. In using the Google Docs spreadsheets, my comment notifications (the orange upper right hand corner in a cell) no longer display, although the comments are still there.

    2. In using the ebill billpay software through my brokerage (Fidelity) I no longer see any icons, just a recessed, grey lined white space where icons used to be. Some example icons were for a calendar to drop down and set a date or a little ebill icon that one could click on to go to the billers site and see the bill. The functionality was gone too.

    Sincerely,

    Tom

    Reply

  13. Valdis Veiders wrote on February 10th, 2010 at 2:28 am:

    :( stoped work my Thinkpad Bluetooth Laser Mouse wheel scrolling in version 3.6, i prefer downgrade to previus version

    Reply

  14. Miller Medeiros wrote on February 11th, 2010 at 7:08 pm:

    I’ve reported 2 bugs related to flash movies:

    overflow:auto gets scrollbar on focused link outline: https://bugzilla.mozilla.org/show_bug.cgi?id=286368#c57

    Mouse wheel scroll on some pages not working when pointer hovers over flash object: https://bugzilla.mozilla.org/show_bug.cgi?id=409669#c16

    Reply

  15. Transcontinental wrote on February 12th, 2010 at 2:47 am:

    Firefox 3.6 new ‘html5.enable’ is set to false by default. Haven’t found much information regarding the opportunity to set it to true. Would be glad to be enlightened on this issue.

    Reply

  16. AJM wrote on February 16th, 2010 at 12:02 am:

    Is it me? Or has any one else noticed that Mozilla, gmail included, freezes alot since the last download. Almost daily now I can count on loosing content because Moziila freezes. I hope this changes soon.

    Reply

    1. Transcontinental wrote on February 17th, 2010 at 12:55 am:

      AJM, I have had as far as I’m concerned not one single freeze nor crash, not one single problem with Firefox 3.6 running on XP SP3 Home (with 80 extensions moreover), and I’ve been running FF 3.6 ever since the moment it was made available. I may add that comments on forums (and I read quite a few) are not particularly talkative regarding what could look like Firefox 3.6 chronic problems; on the contrary :) The “Thing” here is running fast ‘n smooth!

      Reply

  17. Michael wrote on February 18th, 2010 at 10:43 am:

    Not a development issue, but a minor niggling user interface one:

    Why was it necessary to change the default tab-opening behavior to copycat IE? Why was it necessary to not even put the option to revert this behavior under Tools > Options > Tabs?

    Yes, I know, you can go into about:config to change it back to what we’re used to, but that seems gratuitously unnecessary. If I wanted a browser that “looks and feels” like IE in everything down to tab-opening behavior, I’d use frickin’ IE. If you want to give users the *option* for IE tab-opening-next-to-your-tab behavior, great. But forcing all of us who are actually used to the up-til-now-existing Firefox tab behavior to face a random annoying user interface change like this at the update and either adapt or dig through about:config, is poor design.

    Reply

  18. Nigel Duncan wrote on February 18th, 2010 at 11:49 am:

    Nigel Duncan Tel: (34) 91 345 5903
    Jerez 4, P4, 4B Mob: (34) 637 052 031
    E-28016 Madrid Email:nigeldun@gmail.com
    Spain

    I think your developers have been asleep and I am not exactly pleased that, as a customer, I have had to do all the donkey work to provide you with a solution for your benefit, that is if you choose to make use of it. The browsers that work with Sound Pilot and those that don’t are shown below – of course there may be others that also work, but five is enough for me to work with:

    BROWSER SOUND PILOT

    Firefox 3.5.7 No
    IE 8 No
    Firefox Safe Launch No
    Google Chrome No
    Safari for Windows Freezes my Windows
    Avant YES
    Crazy Browser YES
    Flashpeak SlimBrowser YES
    Smart Bro YES
    Maxthon 2 YES

    Nigel Duncan

    PS: I am sending this text to Mozilla and as many others as I can

    Reply

  19. Transcontinental wrote on February 19th, 2010 at 2:10 am:

    Quite true, Michael, I agree. I remember having read somewhere (a source of authority as to what I recall) stating that the new tab-opening behavior was “smarter” (that was the idea) on the long term… I disagree on that, I think preference for a tab-closing behavior is strictly related to one’s preference of organization, like FIFO or FILO…
    Whatever, the choice should be clearly implemented in the Options window.

    Reply

  20. David Kloepper wrote on February 21st, 2010 at 10:28 pm:

    IE Tab is broken under the new version. Coral IE Tab is not an acceptable substitute and IE Tab is no longer supported by the old developer. Millions of Firefox users are affected by this problem. IE Tab is critical to my usage of Firefox, so I will have to abandon all future Firefox developments if this is not fixed.

    Reply

  21. Emily wrote on February 22nd, 2010 at 8:12 am:

    Firefox 3.6 doesn’t seem to be reading the stylesheet on a client’s site of mine:
    http://www.sacredspaceacupuncture.com

    No other sites of mine seem to be affected like this…. and all other browsers are fine, including Firefox 3.5.. well it was until i updated

    (i haven’t debugged in IE for style issues so ignore that for now)

    hmmm…

    Reply

  22. Rudi Olckers wrote on February 22nd, 2010 at 1:01 pm:

    I’m experiencing the same issue as darkyndy. I require an input text field of height e.g. 50px. FF3.6 vertically aligns the input text field value in the middle. This is not happening in FF3.5.8/7, IE7 nor Chrome (where the value is top-aligned). I can do a work around but I have a suspicion that I’m not the only only experiencing this issue as many users have not upgraded to FF3.6 yet. This is a sample of how to reproduce the issue:

    .classA {
    height: 50px;
    background-color: red;
    }

    Reply

  23. Bambu wrote on February 23rd, 2010 at 11:23 am:

    Add me to the list of those who aren’t happy about the new tab behaviour! I would like to see an option to go back to new tab being added to the end of the list of tabs.

    @Michael – what’s the about:config option to return to the old behaviour? I looked at it and didn’t see what could be changed.

    @David Kloepper – what don’t you like about Coral IE Tab? I think it works as well as, if not better than, IE Tab.

    Reply

    1. David Kloepper wrote on February 24th, 2010 at 12:52 pm:

      Check out the myriad of negative comments about Coral IE Tab on the add-ons website at https://addons.mozilla.org/en-US/firefox/addon/10909. Also check out the many distressed comments about the death of the original IE Tab and the inadequacy of Coral at https://addons.mozilla.org/en-US/firefox/reviews/display/1419?show=20&page=16. Coral simply does not (yet?) have the same functionality as the original despite the addition of AdBlock. Perhaps the new developer will fix this. Until then, I will be stuck in a time warp with other Firefox 3.5 users. Or maybe I’ll revert to Opera if security becomes a large issue with 3.5.

      Reply

  24. Bob wrote on February 23rd, 2010 at 3:22 pm:

    I can’t open an iframe in a xul page with this code.

    …

    …

    It works with Firefox 3.5 but not with 3.6…
    Thanks

    Reply

  25. jimmy tardy wrote on February 25th, 2010 at 9:38 am:

    hello,
    for some reason, every time a put my mac to sleep i get kicked off the network and have to reenter my password, have to look up the network even. this never happened until i got FF3.6. Any help?

    Reply

  26. Preston wrote on February 27th, 2010 at 4:17 pm:

    Downloaded 3.6 a few days ago. I used to like this product but after using it for short periods of time it gets slower and slower until it just locks the whole system up. My broadband connection is operating at the same speed I used to get on dial up about 5 years ago. I hope you have some fixes coming. Also, trying to post comment on your feedback site was impossible. The send button never did activate. What is going on with what used to be a good browser?????

    Reply

  27. Chester fitzpatrick wrote on February 27th, 2010 at 6:45 pm:

     

    Hi Chester,

    Unfortunately, all versions of Firefox 3.x have a bug in its
    AppleScript implementation.

    The result is that URL Manager Pro cannot query the current web page
    and the Add Bookmark command does not function.

    Thanks.

    Is there any way to inform Mozilla so they could fix their AppleScript implementation problem? It sure would be great to be able to use URL Manager Pro with Firefox 3.x! :D Let me know.

    Reply

  28. Edward wrote on February 28th, 2010 at 2:10 pm:

    I hope the Mac OS Apple events can be made to work properly with the new Firefox soon..

    Currently there is a problem which does not let it properly integrate with URL manager pro, it is very inconvenient that it is not working.

    Thanks..

    Reply

  29. amaloney wrote on March 1st, 2010 at 7:34 am:

    URL Manager Pro is broken on Firefox 2.6.
    Apparently this has something to do with AppleScript.
    When will Firefox repaired to solve this problem?

    Reply

  30. amaloney wrote on March 1st, 2010 at 7:35 am:

    URL Manager Pro is broken on Firefox 2.6.
    Apparently this has something to do with AppleScript.
    When will Firefox be repaired to solve this problem?

    Reply

  31. Dragon wrote on March 1st, 2010 at 1:57 pm:

    Hey there,
    It seems that Firefox 3.6 has a bug in its AppleScript implementation.

    I am trying to use a program called URL Manager Pro but it cannot query the current web page and the Add Bookmark command does not function which worked perfectly fine in previous versions. Please fix. Thanks.

    DRAGON

    Reply

  32. brooklyn wrote on March 2nd, 2010 at 12:21 pm:

    Since Firefox 3.6, all of the flash based apps on facebook are not working. I checked the apps using Firefox 3.5.8, the apps run.

    is it firefox 3.6 that cause this problem? If not, then how come version 3.5.8 makes flash apps work?

    Reply

  33. Jim O. wrote on March 4th, 2010 at 12:19 pm:

    I’m not a developer.

    Performance with 3.6 is significantly slower – went back to 3.5.8

    Reply

  34. Butch Jones wrote on March 6th, 2010 at 9:22 am:

    I would like to see FIREFOX add a feature that would allow me to customize what the F1-F12 keys can do. I am especially interested in a very simple feature that would allow me to setup/assign my email address to an F-key. Many times I have to enter my email address and one slip of the finger can end up with an incorrect or misspelled address. I would live to be able to go under the TOOLS > OPTIONS > GENERAL > {new tab here} ENTER F-KEY ASSIGNMENT and have a spot to enter my email and assign or remap the F-KEY to this.

    Reply

  35. Alex wrote on March 10th, 2010 at 5:44 am:

    Impossible to get the current URL in Firefox 3.6 using Apple Script (it was possible in 2.x and 3.0 and 3.5)

    Reply

  36. Slim wrote on March 10th, 2010 at 9:25 am:

    Please add the smooth Google Chrome status bar in Firefox 4.

    Reply

  37. Stuart wrote on March 12th, 2010 at 3:19 am:

    Tab seems to broken in Firefox 3.6
    They no longer open at the end of the list iof tabs but open next to the tab they originated from.

    How do I fix this broken behaviour?

    Reply

  38. JT wrote on March 12th, 2010 at 6:32 am:

    Ugh. The new tab behavior is awful. It’s to easy to lose track. FIFO just makes sense. The old way should be the default, and the new method should only be an option. Stop trying to copy the failures of IE.

    Reply

  39. chris wrote on March 12th, 2010 at 7:54 am:

    Hi!

    Mozilla keeps changing interfaces – This is a real pain as we have to keep producing yet another accompanying DLL for each release of firefox. This sort of movement of interfaces is one of the reasons that commercial companies and products shy away from Mozilla.

    For example, in 3.5, your interface IID for IDOMNSELEMENT is f0aef489-18c5-4de6-99d5-58b3758b098c , but then in 3.6 its changed to c9da11bc-32d4-425e-a91f-7e0939c39251 – How can we get around continually having to rebuild with newer items each time you re release your product? If you had a “real” com server instead of XPCOM, the interface IDs would just be in the registry and we could read them back without the continual need for our engineers to play catch up to support mozilla, each time you re release ! tsk.

    Reply

  40. Franz wrote on March 12th, 2010 at 1:24 pm:

    There is almost certainly a regression when using 3.6 to authenticate facebook apps created using the facebook flash/flex libraries. I only ever tested it on 3.6 but have since found at least one other person reporting a problem with 3.6, and many others reporting broken facebook apps starting Jan 2010: they do not specifically blame 3.6 but it’s a likely culprit considering neither api’s nor their code changed around the time 3.6 was introduced. I can confirm my app works on Safari 4, see blog post below for someone else (ny) reporting it working on 3.5.8 but not 3.6

    The behaviour on 3.6 is that, when attempting authentication, it does switch to the browser but never actually opens a tab with the relevant page.

    http://www.gskinner.com/blog/archives/2009/03/adobe_releases.html

    Reply

  41. Claude B. wrote on March 13th, 2010 at 8:36 pm:

    Brooklyn thanks for your comment; I’m with the 3.5.8 and I won’t “Upgrade” till another version 3.6.???

    Reply

  42. Damien Buckley wrote on March 16th, 2010 at 7:17 pm:

    Just encountered a change in 3.6 when using the Web Developer Extension. Whereas in all other versions if you hit ‘images’ > ‘view image information’, a full detail of ALL images is provided, under 3.6 no background images are shown. I went back to 3.5.8 and it works fine and shows all images. Not sure if this is a bug in FF3.6, a setting I need to alter or the WD extension requiring an update?

    Reply

  43. harv8457 wrote on March 17th, 2010 at 4:09 am:

    firefox 3.6 keeps crashing on me. I never had this problem before. Is it possible to go back to an earlier version

    Reply

  44. Jan wrote on March 21st, 2010 at 6:16 am:

    After I updated to firefox 3.6 I am unable to see many sites wich using frames.

    Reply

  45. i. b. Pod wrote on April 16th, 2010 at 12:38 pm:

    Not that I have a lot against yahoo, I just don’t want the tool bar appearing at random intervals on Firefox. If I want it I’ll install it, thank you. One thing that brought me to Mozilla was the high BS factor with IE. Now Moz seems to be copying ms shoveling BS updates full of unwanted mandatory updates pushed on me. Make all the changes you want but please let me decide if i want to use them. If I could I would go back about 8 years to those versions where simple clean workable was the rule. change for change sake isn’t necessarily useful!

    Reply

  46. acacio jr wrote on April 19th, 2010 at 9:40 am:

    Flash Parameter wmode = “transparent” doesn’t work in Firefor 3.6 you crazy!!??

    Reply

  47. Clyde R. Horn wrote on April 22nd, 2010 at 3:55 pm:

    I’ve used Firefox for years but it has incompatibility issues with my computer since the newest updates. My computer refuses to wake up from sleep, I get slow downs in checking my email and crashes. When I remove it and use Windows my computer works fine. I’m sorry but Firefox will no longer be my browser of choice.

    Reply

  48. Rex wrote on April 22nd, 2010 at 7:29 pm:

    I am having constant freezes in firefox 3.6.1 on windows 7 x64. Checking the task manager shows firefox is using 50% of my CPU (on a two-core machine, so it’s locking out one core)
    even typing this message is taking forever because every 38 characters the screen stops responding. Anybody got any tips? This is quite terrible.

    Reply

  49. Kevin wrote on May 4th, 2010 at 1:33 am:

    I had problems with 3.6.x and had to revert back – now using 3.5.9 and everything is fine again including the tab behaviour.

    I won’t be updating again until this reverts back to how it was as I use this a lot – the change is a right pain when you’ve got tons of windows open like I have.

    I run XP Home and it never had a problem with Firefox until 3.6.x – the crashing and freezing makes it unusable.

    To revert back simply download an old version I suggest 3.5.9 and install. Then under Tools > Options > Advanced > Update uncheck the ‘Automatically download and install the update’ button and check ‘Ask me what I want to do’. This will ensure that the new version won’t re-install itself.

    Reply

  50. Jakob Kroeker wrote on May 5th, 2010 at 3:23 am:

    I observe div flickering during the page load process
    under following conditions:

    nested divs are used and the parent div
    has a CSS-Property “overflow:scroll;” or “overflow:auto;”

    Reply

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