In Firefox, what exactly does "Reset Firefox" do?

Question

What exactly does the "Reset Firefox" function do in Firefox? (Firefox->Help->Troubleshooting Information->Reset Firefox) It says that things get reset to their default state -- is there a precise list of things that get reset?

I've been using the same Firefox profile for almost two years, using it across version upgrades. It was recommended that I do a "Reset Firefox", purely for good measure, having amassed a profile across so many versions.

While I'm OK to do this, I don't want to lose my extensions, preferences, history, etc. I've fully backed all of these up with/through extensions "FEBE" and "OPIE". But I'm wondering if, after doing a "Reset Firefox", my restoring of things from my old profile are merely going to bring the outdated/cluttered garbage back to the surface.

Answer 1

See the Reset Firefox – easily fix most problems and Reset Your Firefox articles:

What does the reset feature do?

All of your Firefox settings and personal information are stored in your profile folder. The reset feature works by creating a new profile folder for you while saving your most important data.

Firefox will try to keep the following data:

• Bookmarks
• Browsing history
• Passwords
• Cookies
• Web form auto-fill information

The following items and settings will be restored or removed:

• Extensions and themes: Although they can be incredibly helpful, some extensions and themes can cause problems. If you need to reinstall important extensions, see Find and install add-ons to add features to Firefox for help.
• Open tabs, windows and tab groups: The reset process will close all open websites. Since your bookmarks and browsing history are saved you should still be able to easily return to your favorite sites. See Where can I find my bookmarks? and Awesome Bar - Find your bookmarks, history and tabs when you type in the address bar for more info. Also, since your cookies are saved, you shouldn't be logged out of any websites you were logged in to before the reset.
• Site-specific preferences, search engines, personal dictionary, download history, DOM storage, security certificate settings, security device settings, download actions, plugin MIME types, toolbar customizations and user styles are also not saved. See the Profiles - Where Firefox stores your bookmarks, passwords and other user data article for more information about these.