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Release Notes - Firefox 0.9 (One Tree Hill)

A new version of Firefox is available. Click here to see more information about what's new and to download the latest version.

Firefox is a speedy, full-featured browser that makes browsing more efficient than ever before. More information about Firefox is available.

Firefox 0.9 is a Technology Preview. While this software works well enough to be relied upon as your primary browser in most cases, we make no guarantees of its performance or stability. It is a pre-release product and should not be relied upon for mission-critical tasks. See the License Agreement for more information.

These release notes cover what's new, download and installation instructions, known issues and frequently asked questions for the Firefox 0.9 release. Please read these notes and the bug filing instructions before reporting any bugs to Bugzilla.

We want to hear your feedback about Firefox. Please join us in the Firefox forums, hosted by MozillaZine.

What's New

Here's what's new in this release of Firefox:

  • New Default Theme

    An updated Default Theme now presents a uniform appearance across all three platforms - a new crisp, clear look for Windows users. Finetuning for GNOME will follow in future releases.

  • Comprehensive Data Migration

    Switching to Firefox has never been easier now that Firefox imports data like Favorites, History, Settings, Cookies and Passwords from Internet Explorer. Firefox can also import from Mozilla 1.x, Netscape 4.x, 6.x and 7.x, and Opera. Mac OS X and Linux migrators for browsers like Safari, OmniWeb, Konqueror etc. will arrive in future releases.

  • Extension/Theme Manager

    New Extension and Theme Managers provide a convenient way to manage and update your add-ons. SmartUpdate also notifies you of updates to Firefox.

  • Smaller Download

    Windows users will find Firefox is now only 4.7MB to download.

  • Help

    A new online help system is available.

  • Lots of bug fixes and improvements

    Copy Image, the ability to delete individual items from Autocomplete lists, SMB/SFTP support on GNOME via gnome-vfs, better Bookmarks, Search and many other refinements fine tune the browsing experience.

For Linux/GTK2 Users

  • Installer

    Firefox now comes with an installer for Linux/GTK2 users. The new installer makes the installation process much simpler.

  • Look and Feel Updates

    Ongoing improvements have been made to improve the way Firefox adheres to your GTK2 themes, such as menus.

  • Talkback for GTK2

    Help us nail down crashes by submitting talkback reports with this crash reporting tool.

See The Burning Edge's Bigger Picture for more details.

System Requirements

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

Downloading Firefox provides Firefox binaries for Windows, Linux, and Mac OS X.

Windows: Installer

Linux: GTK2 + XFT installer or GTK2 + XFT (no installer)

Mac OS X: Compressed Disk Image

Contributed builds (These are unofficial builds and may be configured differently than the builds.)

Localized builds Contributed by the volunteers of the MLP:

Installing Firefox

Once you have downloaded a Firefox installer or compressed archive, follow these instructions to install:

First, for these preview releases it is strongly recommended that you uninstall any previous version of Firefox first. Installing over the top of an older version may cause unpredictable problems. If you install over the top of an older version and want to file bugs, please do a clean install into a fresh directory before doing so.


Double click the FirefoxSetup-0.9.2.exe installer to start the install.

NOTE - Do not install Firefox over the top of another Firefox installation. If you want to install Firefox 0.9 into the same folder that you had Firefox 0.8 in, uninstall Firefox 0.8 first. Upgrading will be fixed in a future release.

Mac OS X

Double click the Firefox Compressed Disk Image to mount. Your browser may have already uncompressed the image and mounted it for you. Double click the Firefox 0.9.1 Disk Image and drag the Firefox application onto your hard disk. Drag the icon to your Dock if you want it to appear there.


Extract the tarball and run the installer like so:

tar -xzvf firefox-0.9.1-i686-linux-gtk2+xft.tar.gz
cd firefox-0.9.1-i686-linux-gtk2+xft/

Other Platforms

Extract the compressed archive and run firefox

Uninstalling Firefox

To uninstall Firefox, follow these instructions:


From the Start menu, choose Control Panel. When the Control Panel appears, double click Add or Remove Programs. Find "Mozilla Firefox" in the list and click Remove to uninstall.

Mac OS X

Drag the Firefox application to the Trash.


Remove the firefox folder.

These instructions leave your profile in place in case you install Firefox again in the future. If you wish to remove your Firefox profile folder, follow these instructions:


Locate your Application Data folder, this is usually under Documents and Settings\<username>\Application Data. You may need to make hidden files visible in Windows Explorer, since the Application Data folder is hidden. If your username is "Joe", and your Documents and Settings folder is on C:\, your profile folder is here: C:\Documents and Settings\Joe\Application Data\Mozilla\Firefox. Delete the Firefox folder to remove your profile data.

Mac OS X

Open the Library folder in your Home folder, and remove the Firefox folder. (~/Library/Firefox/).


Remove ~/.firefox.

Changes You Should Be Aware Of

Profile Folder

Firefox now stores your user data in one of the following locations:

WindowsDocuments and Settings\<UserName>\Application Data\Mozilla\Firefox
Mac OS X~/Library/Application Support/Firefox

If you were using Firefox 0.8 as your default browser prior to upgrading to Firefox 0.9, data from your profile will be copied into the new location. You can remove the old "Phoenix" folder at your leisure.

Note to Nightly Build Users

Part way between 0.8 and 0.9, the profile location changed from: Application Data\Firefox (Windows), ~/Library/Firefox (Mac OS X) and ~/.firefox (Linux) to the locations above. When you run 0.9.1 for the first time, information about your profiles will be copied to the new location but the data will not be moved. You must not delete the Application Data\Firefox, ~/Library/Firefox or ~/.firefox folder, since these still hold your profile, and the profiles.ini file at the new location refers back to them. You must move the files yourself manually and hand-edit profiles.ini to update the registry to point to the new location. Users of Firefox 0.8 should not have to worry about this, this is only for community testers and people who have been living on the bleeding edge.

Old Extensions and Themes

To prevent the kind of problems we had with the 0.8 release (users were having the browser not start with "No XBL Binding for Browser" errors, and finding that their theme was broken), when you run 0.9 for the first time all of your extensions will be automatically disabled, and the theme will be reset to the default. You must then look for newer versions of your extensions that are compatible with Firefox 0.9 since the extension API has changed. After Firefox 0.9, these updates should be more seamless.

Known Issues

This list covers some of the known problems with Firefox 0.9. Please read this before reporting any new bugs, and watch it regularly (we'll update it as new bugs are found in the release).

  • If Firefox 0.9 is placed in a location with limited access privileges, it should be run by a user with access to that location first, so that all initial startup files are generated. There may be issues still where if a restricted-access user is the first to run the app, these files may not be generated properly and Firefox may enter an infinite restart loop. This will be fixed in a future release.
  • If Firefox will not display a browser window on Mac OS X, quit Firefox using Cmd+Q and open ~/Library/Application Support/Firefox/Profiles/ and remove localstore.rdf. Restart Firefox. Any toolbar customizations you have made or window placement will be lost
  • We have made some changes to fix security problems involving one site targeting links and form submissions into a frameset created by another site, however these changes may cause problems with some sites. If you encounter problems where sites are trying to use this capability legitimately and you need them to work, you can use about:config and set docshell.frameloadcheck.disabled to true to disable the security check. Please file bugs on the URLs that are problematic, if you encounter any.
  • Firefox utilizes large chunks of Mozilla Application Suite code. Many of the problems you may experience in Firefox are actually problems in this Mozilla core code. If you find a problem with page content or connectivity then it is probably a Mozilla problem and should be reported to the Browser product in Bugzilla, not to the Firefox product.
  • Menus and folders on the bookmark toolbar do not always collapse correctly for Firefox users on Windows.
  • "Use this theme" checkbox in theme install doesn't function properly and you may have to switch themes by selecting Tools > Themes, selecting the Theme you want to use and clicking "Use Theme". Also, some themes will not completely switch without a restart.
  • Users of nightly builds between 0.8 and 0.9, including the Release Candidate, are advised to delete the extensions folder in their profile folder if the application enters an infinite restart loop on startup.
  • Some users have experienced performance problems with the Downloads window - if the Downloads window experiences slow painting, try installing this patch.
  • The Extension Update and Software Update systems have not yet been well tested. You may experience problems. These will be addressed in the 1.0 beta release. As of the time of release, the update service has not been deployed on which means updates will not be available. You may see status notifications for available updates when there are none.

For additional issues, FAQs, Tips and Tricks plus general Firefox help be sure to check out David Tenser's very useful Firefox Help site and the firefox forums hosted by MozillaZine.


It should not be necessary to create a new profile when you upgrade from a previous version of Firefox providing you do disable all extensions from the prior version before upgrading. To do this, open the old version and open Tools > Options and click the Extensions panel. Click on each of the extensions listed and choose Disable Extension. Click OK to close the Options window. Now it is safe to install Firefox.

Once you have installed Firefox, check to see if there are new versions of all of your extensions that are compatible with the new version, and install them. In the future this process may be automated.

If you enable an extension from an older version of Firebird or Phoenix and it causes problems, run the older version of the browser and disable the extension, then run the newer version again.

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 all the exposure we can get. Make it your mission to convert as many of your friends, family members and coworkers as possible. If you're a student, get it distributed at your college. Submit a story to Slashdot and other news sites about the release. Make some noise on your blog. Mass distribution via the Internet is possible -- look at Kazaa. Spread the word!

  2. I use another browser because...

    If you're not using Firefox, tell the development team why. We read the feedback at the Firefox forums.

  3. 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.

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

    Extensions and themes can be downloaded from Mozilla Update.

  5. Who is working on Firefox?

    Currently Ben Goodger and Blake Ross (working for the Mozilla Foundation), Brian Ryner (for IBM), Benjamin Smedberg, Darin Fisher, Pierre Chanial, Dave Hyatt and the wider community contributing to the Mozilla codebase. Asa Dotzler, Leaf Nunes and a team of QA contacts handle bug triage, releases, and other odds and ends. For full details, see the credits in Help > About.

  6. Where's the Firefox source code? Mozilla trunk + mozilla/browser + mozilla/toolkit.

  7. Is Firefox just Mozilla with a couple UI tweaks?

    Firefox is substantially different, featuring a number of exclusive features and countless refinements. Well over 120,000 lines of code have been added or changed in the browser and toolkit CVS directories since the project began.

  8. What happened with the name Phoenix Firebird?

    It had to change because of trademark issues. The new name is Firefox. See the Renaming FAQ for more information.

  9. Where is the mail client?

    Firefox 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.

Previous versions of the Release notes: 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.6.1 | 0.7 | 0.7.1 | 0.8 | 0.9