Troubleshoot and diagnose Firefox problems

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Most problems with Firefox can be fixed by following the troubleshooting methods described below. Try these steps in order. If one doesn't work, move on to the next one. If you need extra help with any of this, we have a community of volunteers standing by.

1. Restart your computer

Sometimes problems can be fixed by simply restarting your computer and then starting Firefox again.

2. Clear your cookies and cache

Many problems with loading web pages can be resolved by clearing Firefox's cookies and cache:

  1. At the top of the Firefox window, click on the Firefox button, go over to the History menu and select Clear Recent History....On the menu bar, click on the Tools menu, and select Clear Recent History....At the top of the Firefox window, click on the Tools menu, and select Clear Recent History....
  2. In the Time Range to clear: drop-down, select Everything.
  3. Click the arrow next to Details to display the list of items that can be cleared.
  4. Select both Cookies and Cache.
  5. Click Clear Now.
  1. At the top of the Firefox window, click on the Firefox button, go over to the History menu and select Clear Recent History....On the menu bar, click on the History menu, and select Clear Recent History....At the top of the Firefox window, click on the History menu, and select Clear Recent History....
  2. In the Time Range to clear: drop-down, select Everything.
  3. Click the arrow next to Details to display the list of items that can be cleared.
  4. Select both Cookies and Cache.
  5. Click Clear Now.
  1. Click the menu button New Fx Menu , choose History and select Clear Recent History....
  2. In the Time Range to clear: drop-down, select Everything.
  3. Click the arrow next to Details to display the list of items that can be cleared.
  4. Select both Cookies and Cache.
  5. Click Clear Now.
For more information, see Delete browsing, search and download history on Firefox.

3. Restart Firefox in Safe Mode

Firefox Safe Mode is a troubleshooting mode that disables all extensions, uses the default theme, turns off hardware acceleration, and uses default toolbar settings and controls, among other things. To start Firefox in Safe Mode:

  1. 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)
  2. In the Firefox Safe Mode dialog, click Start in Safe Mode.
  3. Check whether your problem is still happening while in Safe Mode.

4. Troubleshoot your plugins

Sometimes plugins used in Firefox (such as Adobe Reader, Flash, Java, Silverlight and QuickTime) can cause problems that may be fixed in the latest version. To check to see if you have the latest plugin versions, go to our Plugin Check page. If any of your plugins are outdated, click Update and follow the instructions for updating that plugin. After you've updated all of your plugins, restart Firefox:

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 .

then start Firefox again. If the problem still happens, you can disable all of your plugins to see if one of them is the cause:

  1. At the top of the Firefox window, click on the Firefox buttonOn the menu bar, click on the Tools menuAt the top of the Firefox window, click on the Tools menu, and then click Add-ons. The Add-ons Manager tab will open. Click the menu button New Fx Menu and choose Add-ons. The Add-ons Manager tab will open.

  2. In the Add-ons Manager tab, select the Plugins panel.
  3. Click each plugin in the list and then select Never Activate in its drop-down menu.
  4. Check whether your problem happens when you have all plugins disabled.

If your problem goes away when your plugins are disabled, see the Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems article to learn how to narrow down the cause.

5. Reinstall Firefox

Some Firefox issues can be caused by a problem with one of the Firefox program files. Follow these steps to completely remove and reinstall Firefox. This process will not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

Note: You might want to print these steps or view them in another browser.
  1. Download the latest official version of Firefox from mozilla.org.
  2. Exit Firefox:

    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 .

  3. Uninstall Firefox from your computer.
  4. Delete the Firefox program folder, which is located in one of these locations by default:
    • C:\Program Files\Mozilla Firefox
    • C:\Program Files (x86)\Mozilla Firefox
  5. Reinstall Firefox - see How to download and install Firefox on Windows for instructions.
  1. Download the latest official version of Firefox from mozilla.org.
  2. Quit Firefox:

    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 .

  3. Uninstall Firefox from your computer by opening the Applications folder in the Finder and dragging the Firefox application to the Trash.
  4. Reinstall Firefox - see How to download and install Firefox on Mac for instructions.
  1. Download the latest official version of Firefox from mozilla.org.
  2. Quit Firefox:

    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 .

  3. Uninstall Firefox - If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux for details. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory to uninstall Firefox.
  4. Reinstall Firefox - see Install Firefox on Linux for instructions.

Now start Firefox and check to see if your problem has been fixed.If it hasn't, continue with the next troubleshooting method.

6. Refresh Firefox

The Refresh Firefox feature can fix many issues by restoring your Firefox profile to its default state while saving your essential information.

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 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. 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.

7. Create a new Firefox profile

Sometimes files in your Firefox profile folder that correspond to the essential information that a Firefox Refresh doesn't remove (such as bookmarks and browsing history) may be causing the issue. You can create a new, additional profile which will not contain any of your old Firefox data. See Use the Profile Manager to create and remove Firefox profiles for instructions.

Other solutions

If you've tried all of these troubleshooting methods and you're still having problems the issue may be with other software or hardware.

This section does not contain step-by-step instructions. For more information on any of these solutions, please check the related documentation.

Check for conflicts with your Internet security software

Some Internet security software (including antivirus, antispyware, and firewall programs) can cause problems with Firefox including blocking it from opening websites, crashes, and more. Often you can open the program's settings, remove Firefox from its list of allowed or trusted programs and it will be re-detected and things should start working again. If your program is listed at the Configure firewalls so that Firefox can access the Internet article, you can get specific instructions for how to properly reconfigure it.

Scan your system for viruses and spyware

Periodically, you should scan your system for viruses, spyware, or other malware. These free malware removal tools are often useful:

If you need more help removing malware, see Troubleshoot Firefox issues caused by malware.

Check your hard drive and RAM for errors

A problem with your computer's hard drive or RAM may prevent Firefox from running or make it crash repeatedly. Here are instructions or tools for checking:



Based on information from Standard diagnostic - Firefox (mozillaZine KB)

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