What resetting Firefox does

Resetting Firefox returns your browser to the state it was in when you first installed it. This clears your browsing history, cookies, cached files, and temporary data. It also removes extensions you added, resets your homepage and search engine back to Firefox defaults, and closes any open tabs or windows.

Your saved passwords, bookmarks, and autofill information are preserved by default during a reset — Firefox keeps these in a separate folder. If you want to remove those too, you can delete them separately after the reset, or choose to wipe everything during the process.

A reset is useful when Firefox runs slowly, crashes frequently, or behaves strangely. It can also help if you want to remove toolbars or extensions that won't uninstall normally, or if you're handing the browser off to someone else and want a clean slate.

Key Takeaways

  • Firefox reset removes extensions, clears browsing data, and resets your homepage and search engine, but keeps passwords and bookmarks unless you choose otherwise.
  • You can reset Firefox from the Help menu without downloading anything or restarting your computer.
  • Firefox creates a backup folder of your old settings on your desktop, so you can recover bookmarks or passwords if you change your mind.
  • If Firefox won't open at all, you can reset it by renaming a folder in your user profile directory.

Reset Firefox from the menu (the standard way)

Open Firefox and click the menu button — three horizontal lines in the top right corner. Select Help, then choose More troubleshooting information. This opens the Troubleshooting Information page.

Scroll down to the section labeled Give Firefox a tune up. Click the button that says Refresh Firefox. A dialog box will appear asking you to confirm. Click Refresh Firefox again to proceed.

Firefox will close, perform the reset, and reopen automatically. The process usually takes less than a minute. When it finishes, you'll see a new tab explaining what was removed and what was kept.

What Firefox saves and what it removes

Firefox automatically preserves your saved passwords, bookmarks, browsing history, autofill data, and open tabs during a reset. Your user profile — the folder that holds all your Firefox data — stays in place, but temporary files and cache are cleared out.

Extensions, themes, and toolbar customizations are removed. Your homepage, search engine, and new tab settings return to Firefox defaults. Cookies from websites are deleted, which means you'll be logged out of most sites you visit.

If you want to keep your bookmarks but remove everything else, or if you want to delete your passwords too, you can manage these choices after the reset completes. Firefox doesn't give you granular options during the reset itself — it's all or nothing for most settings.

Recover your old settings from the backup folder

When Firefox resets, it creates a backup folder on your desktop called something like Old Firefox Data. This folder contains your previous profile, including bookmarks, passwords, and extensions from before the reset.

If you need to recover something, open that folder and look for a subfolder with a random name like 7x8y9z1a.default. Inside you'll find places.sqlite (bookmarks and history), logins.json (passwords), and other profile files. You can copy these back into your current Firefox profile if needed, though the process requires some manual steps.

The backup folder stays on your desktop until you delete it. You can safely remove it once you're confident you don't need anything from it.

Reset Firefox when it won't open

If Firefox crashes on startup or won't open at all, you can still reset it without using the menu. Close Firefox completely, then locate your profile folder. On Windows, press Windows key + R, type %appdata%\Mozilla\Firefox\Profiles, and press Enter. On Mac, open Finder, press Command + Shift + G, paste ~/Library/Application Support/Firefox/Profiles, and press Enter. On Linux, open your file manager and navigate to ~/.mozilla/firefox.

You'll see a folder with a name like 7x8y9z1a.default-release. Right-click it, select Rename, and add .old to the end of the name — for example, 7x8y9z1a.default-release.old. Then open Firefox. It will create a brand new profile folder and start fresh.

Your old profile folder (the one you renamed) stays in place as a backup. Once Firefox is running smoothly, you can delete it.

When to reset versus when to try other fixes first

A reset is a last resort. Before you reset, try closing all tabs and restarting Firefox — this fixes many slowness and crash problems. If Firefox is still sluggish, disable extensions one at a time to find the culprit. You can do this by clicking the menu, selecting Add-ons and themes, then Extensions, and toggling each one off.

If a specific website is broken or won't load, clear your cache and cookies for just that site instead of resetting everything. Click the menu, go to Settings, then Privacy & Security, scroll to Cookies and Site Data, click Manage Data, search for the site name, and click Remove Selected.

Reset Firefox only if the browser is consistently unstable, if you can't remove an unwanted extension, or if you're preparing to give it to someone else.

Frequently Asked Questions

Will I lose my bookmarks if I reset Firefox?

No. Firefox keeps your bookmarks during a reset. They'll be in the same folders after the reset completes. If you want to delete them too, you can do that separately afterward by going to Bookmarks, right-clicking a folder, and selecting Delete.

Can I undo a reset?

Yes, if you act quickly. Firefox creates a backup folder on your desktop called Old Firefox Data. You can copy bookmarks, passwords, or other files from that folder back into your current Firefox profile. After a few weeks, you can safely delete the backup folder.

Do I need to uninstall and reinstall Firefox to reset it?

No. The reset feature in the Help menu does everything you need without uninstalling. Uninstalling and reinstalling is slower and may not remove all your old settings anyway.

Will resetting Firefox remove viruses or malware?

A Firefox reset removes browser extensions and toolbars that might be malicious, but it won't remove malware from your computer itself. If you suspect a virus, run a full system scan with your antivirus software in addition to resetting Firefox.

What if I reset Firefox but it's still crashing?

If Firefox crashes even after a reset, the problem may be with your computer's hardware, drivers, or other software. Try updating Firefox to the latest version, check for Windows or system updates, and run a malware scan. If crashes continue, contact Firefox support or consult a technician.