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.

• If changes to preference settings are not saved when you restart Firefox, see How to fix preferences that won't save.

To reset preferences:

Click the menu button , click help 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.
   
   
   
   
   
   
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.

• If changes to preference settings are not saved when you restart Firefox, see How to fix preferences that won't save.

Solution 1: Reset Firefox to its default state

Solution 2: Delete Firefox preference files

Click the menu button , click help 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.
   
   
   
   
   
   
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 , click help and select Troubleshooting Information. The Troubleshooting Information tab will open.

2. Under the Application Basics section, click on Show FolderShow in FinderOpen Directory. A window with your profile filesfolder will open.
Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.

3. 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 and then click ExitQuit

4. 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.
5. You can close the profile folder and open Firefox now.