Reset Firefox preferences to troubleshoot and fix problems

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  • Revision id: 51290
  • Created:
  • Creator: AliceWyman
  • Comment: You can also rename the prefs.js file instead of deleting it - see discussion
  • Reviewed: Yes
  • Reviewed:
  • Reviewed by: ideato
  • Is approved? Yes
  • Is current revision? No
  • Ready for localization: Yes
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  • Readied for localization by: ideato
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When troubleshooting Firefox problems, resetting preferences (zoom, tabs, privacy, network, encryption, download actions, etc.) is one of many procedures that can be helpful in pinpointing the issue. This article explains how to use Safe Mode to reset preferences.

To reset preferences:

At the top of the Firefox window, click the Firefox button, go over to the Help menuOn the menu bar, click the Help menuAt the top of the Firefox window, click the Help menu and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.
Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.holding down the option key while starting Firefox.quitting Firefox and then going to your Terminal and running: firefox -safe-mode
You may need to specify the Firefox installation path (e.g. /usr/lib/firefox)
Click the menu button New Fx Menu , click help Help-29 and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.
Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.holding down the option key while starting Firefox.quitting Firefox and then going to your Terminal and running: firefox -safe-mode
You may need to specify the Firefox installation path (e.g. /usr/lib/firefox)

  1. Click to put a check mark by Reset all user preferences to Firefox defaults.

    89a0533be70261469542ad18a5b0fa00-1259976432-945-1.png


    89a0533be70261469542ad18a5b0fa00-1256947708-467-1.png
  2. To apply your changes, click Make Changes and Restart.

Firefox will restart with your preference settings changed back to the defaults.

Resetting preferences (zoom, tabs, privacy, network, encryption, download actions, etc.) is one of many procedures that can be helpful in fixing Firefox issues. There are two ways to do this - reset Firefox to it's default state or delete the preference files. We'll explain both methods.

Solution 1: Reset Firefox to its default state

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.When using the reset 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.When using the reset feature, your bookmarks, browsing history, passwords, cookies and web form auto-fill information will be saved. However, your extensions and themes will be removed; open tabs, windows and tab groups will not be saved; 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

At the top of the Firefox window, click the Firefox button, go over to the Help menuOn the menu bar, click the Help menuAt the top of the Firefox window, click the Help menu and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.
Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.holding down the option key while starting Firefox.quitting Firefox and then going to your Terminal and running: firefox -safe-mode
You may need to specify the Firefox installation path (e.g. /usr/lib/firefox)
Click the menu button New Fx Menu , click help Help-29 and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.
Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.holding down the option key while starting Firefox.quitting Firefox and then going to your Terminal and running: firefox -safe-mode
You may need to specify the Firefox installation path (e.g. /usr/lib/firefox)

  1. Click to put a check mark by Reset all user preferences to Firefox defaults.

    89a0533be70261469542ad18a5b0fa00-1259976432-945-1.png


    89a0533be70261469542ad18a5b0fa00-1256947708-467-1.png
  2. To apply your changes, click Make Changes and Restart.

Firefox will restart with your preference settings changed back to the defaults.

  1. At the top of the Firefox window, click on the Firefox button, go over to the Help menuOn the menu bar, click on the Help menuAt the top of the Firefox window, click on the Help menu and select Troubleshooting Information. The Troubleshooting Information tab will open.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. At the top of the Firefox window, click on the Firefox button and then select ExitAt the top of the Firefox window, click on the File menu and then select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.

    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.