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Firefox Release Notes

Firefox 2 is the next-generation release of the award-winning Firefox web browser from Mozilla.

These Release Notes cover what's new, download and installation instructions, known issues and frequently asked questions for Firefox 2. Please read these notes and the bug filing instructions before reporting any bugs to Bugzilla.

Give us your feedback through this feedback form.

What's New in Firefox

  • Release Date: December 19, 2006

  • Security Update: The following list of security issues have been fixed.

  • Windows Vista Support: Windows Vista is generally supported with the following caveats.

  • Firefox 2 What's New: For an overview of new features in Firefox 2, see the Firefox 2 Release Notes.

Downloading and Installing

System Requirements

Before installing, make sure your computer meets the system requirements.

Downloading Firefox 2 provides Firefox 2 for Windows, Linux, and Mac OS X in a variety of languages. You can get the latest version of Firefox 2 here. For builds for other systems and languages not provided by, see the Contributed Builds section at the end of this document.

Installing Firefox 2

Please note that installing Firefox 2 will overwrite your existing installation of Firefox. You won't lose any of your bookmarks or browsing history, but some of your extensions and other add-ons might not work until updates for them are made available.

Removing Firefox 2

You can remove Firefox 2 through the Control Panel in the Start Menu on Windows, by removing the Firefox application on OS X, or by removing the firefox folder on Linux.

Removing Firefox 2 won't remove your bookmarks, web browsing history, extensions or other add-ons. This data is stored in your profile folder, which is located in one of the following locations depending on your operating system:

Windows 2000, XP, Server 2003 Documents and Settings\<UserName>\Application Data\Mozilla\Firefox
Windows NT WINNT\Profiles\<UserName>\Application Data\Mozilla\Firefox
Windows 98, ME Windows\Application Data\Mozilla\Firefox
Mac OS X ~/Library/Application Support/Firefox
Linux and Unix systems ~/.mozilla/firefox

Any version of Firefox that you install after removing Firefox 2 will continue to use the data from this profile folder.

Extensions and Themes

Extensions installed under Firefox 1.5 may be incompatible and/or require updates to work with Firefox 2. Please report any issues to the maintainer of the extension. When you install Firefox 2 all of your Extensions and Themes will be disabled until Firefox 2 determines that either a) they are compatible with the Firefox 2 release or b) there are newer versions available that are compatible.

Known Issues

This list covers some of the known problems with Firefox 2. Please read this before reporting any new bugs.

All Systems
  • Some firewall software may silently block Firefox from running. This often happens immediately after Firefox has been installed or updated from a previous version. There are configuration instructions available for most popular firewall programs to help you ensure that Firefox is allowed to connect to the Internet.
  • Dictionaries for several locales can't be packaged with the builds, and must be manually downloaded by right-clicking in a text area and selecting "Add Dictionaries..." from the shortcut menu. New dictionaries are regularly being added to Mozilla Add-ons, so if you don't see the particular dictionary you need, check back later.
  • When trying to print web pages with text areas, if the text area contains a misspelled word and spell checking is enabled, all the following content of the text area will not be printed. You can right-click in the text area and uncheck "Spell check this field" to turn off spell checking temporarily while you print.
  • Access key definitions provided by web pages can now be triggered using Alt+Shift+key on Windows, Ctrl+key on Mac OS X, and Ctrl+Shift+key on Unix.
  • The Session Restore functionality provided in Firefox 2 will restore connections to services which use session cookies to maintain login state such as GMail. It is recommended that users with concerns about the privacy implications of this behavior change the value of browser.sessionstore.resume_from_crash to false.
  • The option for "Shrink to fit" has been removed in Firefox 2. If you wish to change this from the value you had set in your previous version of Firefox, change the value of browser.enable_automatic_image_resizing.
  • To install Firefox on a multi-user system in a location in which users do not have write privileges, Firefox must be run at least once by a privileged user. Alternatively, an empty file must be created in the following directory: <install-directory>/extensions/
  • Software Update will not work if Firefox is installed to a location on your disk to which you do not have write access, since Software Update needs to replace or create files in this location.
  • Some financial institutions use port 563 for secure logins, which results in an error message. If you encounter this error, make sure that includes 563 in the comma-separated list of banned network ports to override.
Windows & Windows Vista
  • If the browser is installed in a non-default location, software updates may fail. You can reinstall the software to the default location, or to a non-default location as long as the install folder is named "Mozilla Firefox". Alternatively, you can start Firefox by right-clicking on its icon and selecting "Run as administrator" from the menu.
  • When you launch the browser after it has downloaded a software update, you may get a dialog asking to permit "updater.exe" to run. If you do not allow this operation, the software update will fail.
  • Firefox can not yet be set as the default browser on Vista. See this bug for more information.
  • When installing as a restricted-access user on a shared machine into a location that you can write to, there may still be negative side effects (default browser/other keys not being set correctly). When installing as a restricted access user do not attempt to install over an existing installation in a restricted-access/shared location as this may destroy that installation.
  • Firefox may hang when closing after viewing a PDF file in some older versions of the Adobe Acrobat Reader plug in. If you experience this, make sure you are using the newest version of the plug in.
  • The Update directory on Windows Vista is located under the user's directory, in AppData\Roaming\Mozilla\Firefox\Updates\.
  • Other known issues with Windows Vista can be found in the Vista tracking bug.
Mac OS X
  • The "Close Other Tabs" action on the shortcut menu of a tab can fail with an error when more than 20 tabs are open.
  • Some users have reported problems viewing Macromedia Flash content on Intel Mac computers. To work around this problem, users can remove or move the PowerPC version of "Flash Player Enabler.plugin from /Library/Internet Plug-Ins.
  • After installing a new plug-in, Firefox may continue to display information for the older version of the plug-in in about:plugins. If this happens, quit Firefox, delete the "pluginreg.dat" file from your profile folder, and relaunch Firefox.
  • Java does not run on Intel Core processors under Rosetta.
  • There is no Talkback on Intel-based Macs when running natively or under Rosetta. The Apple Crash report program should launch in the event of application crashes.
Linux and Unix
  • If Firefox is installed to a location with spaces in the path, it may not be able to set itself as default browser and may keep prompting at startup. The work around is to install into a path without spaces.
  • GNOME integration does not work properly with Fedora Core 3. Users of Fedora Core 3 will need to download and install linc-1.0.3-3.1.i386.rpm. After installing the RPM, perform the following command in the directory in which you installed Firefox (you will need write permission):

    touch .autoreg

    The next time you start Firefox, GNOME integration should be functional.
  • firefox -remote (mozilla-xremote-client) no longer works on urls containing commas, and is deprecated. firefox -new-window /url/ will open the url in a new window; firefox -new-tab /url/ will open the url in a new tab.


  • Poorly designed or incompatible Extensions can cause problems with your browser, including make it crash, slow down page display, etc. If you encounter strange problems relating to parts of the browser no longer working, the browser not starting, windows with strange or distorted appearance, degraded performance, etc, you may be suffering from Extension or Theme trouble. Restart the browser in Safe Mode. On Windows, start using the "Safe Mode" shortcut created in your Start menu or by running firefox.exe -safe-mode. On Linux, start with ./firefox -safe-mode and on Mac OS X, run:

    cd /Applications/
    ./firefox-bin -safe-mode

    When started in Safe Mode all extensions are disabled and the Default theme is used. Disable the Extension/Theme that is causing trouble and then start normally.

If you uninstall an extension that is installed with your user profile (i.e. you installed it from a Web page) and then wish to install it for all user profiles using the -install-global-extension command line flag, you must restart the browser once to cleanse the profile extensions datasource of traces of that extension before installing with the switch. If you do not do this you may end up with a jammed entry in the Extensions list and will be unable to install the extension globally.

If you encounter strange problems relating to bookmarks, downloads, window placement, toolbars, history, or other settings, it is recommended that you try creating a new profile and attempting to reproduce the problem before filing bugs. Create a new profile by running Firefox with the -P command line argument, choose the "Manage Profiles" button and then choose "Create Profile...". Migrate your settings files (Bookmarks, Saved Passwords, etc) over one by one, checking each time to see if the problems resurface. If you do find a particular profile data file is causing a problem, file a bug and attach the file.

Frequently Asked Questions

  1. What can I do to help?

    We need help from developers and the testing community to provide as much feedback as possible to make Firefox even better. Please read these notes and the bug filing instructions before reporting any bugs to Bugzilla. You can also give us your feedback through this feedback form.

  2. Why haven't you responded to the mail I sent you?

    Use the forums. The Firefox team reads them regularly. We all get a lot of email and your email may get lost.

  3. Where can I get extensions and themes (add-ons)?

    Extensions and Themes can be downloaded from Firefox Add-ons.

  4. Who makes Firefox 2?

    Lots of people. See Help->About Mozilla Firefox, Credits for a list of some of the people who have contributed to Firefox 2.

  5. Where's the Firefox 2 source code?

    A tarball of the Firefox 2 source code is available for download. The latest development code can be obtained by cvs. Firefox-specific source is in "mozilla/browser", "mozilla/toolkit", and "mozilla/chrome". Please follow the build instructions.

  6. Where is the mail client?

    Firefox 2 works with whatever mail client is the default on your system. However, we recommend Mozilla Thunderbird, our next-generation email client and the perfect complement to Firefox.

Contributed Builds

These are unofficial builds and may be configured differently than the official builds. They may also be optimized and/or tested for specific platforms.

Solaris (contributed by SUN Desktop Beijing Team)

Tarball format (README)

Pkgadd format (README)

Localized Builds

Many localized builds are now produced and distributed by on behalf of their authors. These are available on the Firefox 2 download page.

Builds that have not yet been certified as official Firefox 2 localizations are available by browsing the FTP site.

The following resources contain useful information about Firefox 2: