Session Restore

Firefox 2 comes with a built in Session Store feature that saves your session data including open windows and tabs, window size and position, and text typed in forms. Session data is stored in the "sessionstore.js" file, located in the profile folder. To disable this feature, set browser.sessionstore.enabled to "false".

Default behavior

By default, Firefox will offer to restore your session after a crash. It will automatically restore your session after an automatic update, or when using the restart button from the Add-ons Manager.

Always restore sessions on start

By default this feature is off, but can be turned on from the Options/Preferences menu. In the Main panel, under Startup set "When Firefox starts" to "Show my windows and tabs from last time". This will have Firefox restore your tabs and form data to their state when Firefox closed (the related preference is browser.startup.page).

If you want Firefox to restore multiple windows you need to close Firefox via File -> Exit. Closing the windows one at a time will cause Firefox to only restore the last window that was closed.

Restoring a session once

Set browser.sessionstore.resume_session_once to "true" in about:config and it will restore your session the next time you start Firefox, but not again.

Firefox keeps crashing after restoring a session

If a site's content caused your crash (e.g. a plugin is crashing) restoring your session may restore that page and cause Firefox to crash again. If Firefox keeps crashing after choosing "Restore Session," choose "Start New Session."

External links

• Session Restore at wiki.mozilla.org
• Session store API at developer.mozilla.org