Go back to an old version of Firefox

This article describes how to go back to a old version of Firefox. See this article if you want to go back to an old version of Thunderbird.

Previous maintained version

Firefox 3.6 was the previous version of Firefox that was still being maintained with security and stability updates. At time of writing, Firefox 3.6.28 is still available at http://www.mozilla.com/firefox/all-older.html but, as of April 24th, 2012, it has reached its "end of life" and there will be no further Firefox 3.6.xx updates. [1]

Old version

Starting with the release of Firefox 5, the previous released version (e.g., Firefox 4) is no longer maintained and becomes obsolete. Since the release of Firefox 6, Firefox 5 is also no longer maintained; with the release of Firefox 7, Firefox 6 becomes obsolete, and so on. Although you can still download these old, obsolete Firefox versions, they contain security vulnerabilities and are unsafe browsers.

To downgrade to an old version of Firefox, back up your Firefox profile first, as a precaution, and then follow these steps:

1. Download the version you want from http://download.cdn.mozilla.net/pub/firefox/releases/ or http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/ Note: If you are looking for an older version of a Firefox "final" release, look for a download with no letter suffix (e.g., 18.0.2 is the last final release version previous to 19.0). Release versions that end in esr (e.g., Firefox 17. 0.3esr) are Extended Support Release versions intended for organizations. Versions that end in b (e.g., 19.0b6) are Beta releases, intended for users who are testing pre-release versions.
2. Exit Firefox and then uninstall it. Make sure to remove the Firefox installation directory.
3. Install the older Firefox version. You can install Firefox in the same location to minimize any side effects. For example, the Windows registry or other installed programs may expect Firefox to be in the default location (e.g., C:\Program Files\Mozilla Firefox or C:\Program Files (x86)\Mozilla Firefox on 64-bit Windows).
4. After installing the older version, turn off the automatic Firefox Software Update feature (if enabled).
5. Reconfigure your firewall if you have one.
6. If Firefox disables any of your add-ons you probably need to replace it with a version that supports a older version of Firefox.
7. If you experience other problems, create a new Firefox profile and transfer your data to the new profile.

There are real security problems (actual exploits in the real world) with old versions of Firefox. Rather than downgrading to an older, unmaintained version, you should consider switching to SeaMonkey, Google Chrome or Opera. See the Mozilla Security Advisories page for more information about vulnerabilities in old versions of Firefox.

If you must install an old version of Firefox:

• Make certain you keep the plugins up to date by periodically visiting the Mozilla PluginCheck page.
• There are increasing numbers of Flash and PDF exploits. If you can't keep your plugins updated, either disable the plugin or find an alternative such as using the Foxit reader to view the PDF file in a separate window rather than using the Adobe plugin to view it in the browser window.
• Install either the NoScript add-on (recommended) or the YesScript add-on

See also

• Browser will not start up
• Default browser
• Firewalls
• Transferring data to a new profile - Firefox
• Updating add-ons
• Unable to install themes or extensions
• Uninstalling add-ons
• Uninstalling_toolbars

External links

• Installing a previous version of Firefox (Firefox Support Knowledge Base)
• Add-ons are disabled after updating Firefox (Firefox Support Knowledge Base)
• Addon Compatibility Reporter extension for Firefox. Can be used to enable incompatible extensions.
• Burning Edge (tracks Firefox bug fixes)
• Mozilla wiki page that tracks recent and in-progress releases