Reset Firefox preferences to troubleshoot and fix problems

Resetting preferences (zoom, tabs, privacy, network, encryption, updates, where to save file downloads, etc.) is one of many procedures that can be helpful in troubleshooting Firefox problems. We'll explain two ways to do this.

Solution 1: Refresh Firefox

Note: When using the refresh feature, your bookmarks, browsing history, open tabs, windows, passwords, cookies and web form auto-fill information will be saved. However, your extensions and themes will be removed and your preferences will be reset. Learn more.
  1. Click this Refresh Firefox button directly, if you are viewing this page in Firefox.
    This won't work if you are using a different browser or on a mobile device.
  2. To continue, click Refresh Firefox in the confirmation window that opens.
  3. Firefox will close to refresh itself. When finished, a window will list your imported information. Click Finish and Firefox will open.

Note: There's also a Refresh Firefox button in the Firefox Safe Mode window, if you can't start Firefox normally. You can also do a manual refresh by creating a new profile and transferring your important data to the new profile.

Solution 2: Delete Firefox preference files

  1. Click the menu button Fx57menu , click Help and select Troubleshooting Information.From the Help menu, choose Troubleshooting Information. The Troubleshooting Information tab will open.

    • Under the Application Basics section, click on Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.
    Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.
  2. Click the menu button New Fx Menu and then click ExitQuit Close 29 .

    Click the Firefox menu Fx57Menu , then click Exit. Click the Firefox menu at the top of the screen, then click Quit Firefox.Click the Firefox menu Fx57Menu , then click Quit.

  3. Locate and delete the file prefs.js (or rename it, for example, to prefs.jsOLD, to keep the old file as a backup). If you find more than one, a prefs.js.moztmp file or a user.js file, delete (or rename) these as well.
  4. You can close the profile folder and open Firefox now.
// These fine people helped write this article:AliceWyman, Chris Ilias, David Tenser, Tonnes, Jan., Michael Verdi, Swarnava Sengupta, Lan. You can help too - find out how.

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