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Firefox Lorentz Release Notes Release Notes

Firefox "Lorentz" provides uninterrupted browsing for Windows and Linux users when there is a crash in the Adobe Flash, Apple Quicktime or Microsoft Silverlight plugins.

Testing beta builds of Firefox helps ensure that they are secure and stable for hundreds of millions of users around the world. Please let us know if you experience any new problems, either using this feedback form or by filing a bug in Bugzilla.

What’s New in Firefox Lorentz

Firefox Lorentz is built on Firefox 3.6.3, and includes a new feature for Windows and Linux users which runs the Adobe Flash, Apple Quicktime and Microsoft Silverlight plugins in a separate process.

With this feature if one of these plugins crashes or hangs, Firefox will continue running and you can reload the page to try again.

System Requirements

Before installing, make sure your computer meets the system requirements. The multi-process plugin feature is only available on Linux and Windows XP and above.


If you do not wish to participate in the beta program, you can get the latest version of Firefox 3.6 here.


Please note that installing Firefox Lorentz 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. You can reinstall an older version later if you wish to downgrade.


You can remove Firefox Lorentz 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.

By default, removing Firefox Lorentz won’t remove your bookmarks, web browsing history, extensions or other add-ons. This data is stored in your profile folder, which can be found by going to the Help menu and selecting Troubleshooting Information.... The button next to the Profile Directory line in Application Basics will open your profile directory in your system's file explorer.

Please note that if you keep your profile, any version of Firefox that you install after removing Firefox Lorentz will continue to use the bookmarks, web browsing history, add-ons, and other data from this profile folder.

Extensions and Themes

Extensions installed under Firefox 3.6 should continue working with Firefox Lorentz. Please report any issues to Mozilla and to the maintainer of the extension.

Known Issues

This list covers some of the known problems with Firefox Lorentz, which will be resolved in future releases:

All Systems
  • If you have the "reading pane" option set in Hotmail, the scroll arrows will not work properly (see bug 511075)
  • If FIPS mode is enabled and certain files have been removed from the system, the browser may crash on startup (see bug 522041)
Microsoft Windows
  • The Silverlight showcase does not accept mouse clicks. This is a bug in the Silverlight plugin interacting with Firefox 3.6. (see bug 536429).
Linux and Unix
  • Firefox may have difficulty playing system sounds in some distributions of Linux (see bug 536996)
  • Zooming out on some sites may result in grey or black lines appearing (see bug 468496)


  • 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.

    It is especially important to submit any crash reports when Firefox shows that a plugin has crashed.

  2. Why aren't multi-process plugins available on Mac?

    Mozilla is working on making multi-process plugins available on Mac. Because of architectural differences, the code is not ready for beta testing.

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

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

  4. Who makes Firefox?

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

  5. Where’s the Firefox Lorentz source code?

    A tarball of the Firefox 3.6 source code is available for download. The latest development code can be obtained through Mercurial. Firefox-specific source is in mozilla-central's "browser", "toolkit", and "chrome" directories. Please follow the build instructions.

  6. 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.