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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 the menu button New Fx Menu and then click help Help-29 .
  2. From the Help menu choose Troubleshooting Information.
    If you're unable to access the Help menu, type about:support in your address bar to bring up the Troubleshooting Information page.
  3. Click the Refresh Firefox button in the upper-right corner of the Troubleshooting Information page.
    Refresh 35 Win Refresh 35 Mac Refresh 35 Lin
  4. To continue, click Refresh Firefox in the confirmation window that opens.
  5. 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. If you are unable to find the Refresh Firefox button on your version of Firefox, you can also do a manual refresh by creating a new profile. See instructions on how to create a new profile.

Solution 2: Delete Firefox preference files

  1. Click the menu button New Fx Menu , click help Help-29 and select Troubleshooting Information. The Troubleshooting Information tab will open.

  2. Under the Application Basics section, click on Show FolderOpen FolderShow in FinderOpen Directory. A window with your profile filesfolder will open.
  3. Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.
  4. Click the menu button New Fx Menu and then click ExitQuit Close 29 .
  5. 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.
  6. You can close the profile folder and open Firefox now.
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