

Addon Compatibility Reporter extension for Firefox.Add-ons are disabled after updating Firefox (Firefox Support Knowledge Base).Installing a previous version of Firefox (Firefox Support Knowledge Base).Transferring data to a new profile - Firefox.Install either the NoScript add-on (recommended) or the YesScript add-on.If you can't keep your plugins updated, disable the plugin. There are increasing numbers of Flash and Java exploits.Make certain you keep the plugins up to date by periodically visiting the Mozilla PluginCheck page.

If you must install an old version of Firefox: You should also consider installing the latest Extended Support Release version. Rather than downgrading to an older, unmaintained version, you should consider switching to the latest version of SeaMonkey, Google Chrome or Opera. See the Mozilla Security Advisories page for more information about vulnerabilities in old versions of Firefox. There are real security problems (actual exploits in the real world) with old versions of Firefox. Although you can still download these old, obsolete Firefox versions, they contain security vulnerabilities and are unsafe browsers. Previous released versions of Firefox are no longer maintained and become obsolete.

Versions that end in b (e.g., 19.0b6) are Beta releases, intended for users who are testing pre-release versions. 0.3esr) are Extended Support Release versions intended for organizations. Release versions that end in esr (e.g., Firefox 17.
