This article covers the situation where Firefox displays a message about crashing when you try to quit or exit the program. The crash message may look like one of the following:

Alternately, Firefox may close but display a message similar to the following when you restart it:

• Your last Firefox session closed unexpectedly. You can restore the tabs and windows from your previous session or start a new session if you think the problem was related to a page you were viewing.

If you are seeing crash related messages in another context, please see our general Firefox crashes article for links to pages that may address your specific symptoms better.

Problematic extensions

The most common cause of a crash on exit or improper shutdown is extensions. Our article on Troubleshooting extensions and themes should help in identifying the extension at fault.