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.

Note: Check this list of the latest Firefox issues to see if the problem you are seeing has a solution.

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. Click the menu button Fx89menuButton to open the menu panel.
  2. Click History and select Clear Recent History…
  3. In the Time Range to clear: drop-down, select Everything.
  4. Below the drop-down menu, select both Cookies and Cache. Make sure other items you want to keep are not selected.
  5. Click OKClear Now.
For more information, see Delete browsing, search and download history on Firefox.

3. Restart Firefox in Safe Mode

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. Click the menu button Fx89menuButton, click Help, select Troubleshoot Mode… and click Restart in the Restart Firefox in Troubleshoot Mode? dialog.

    Note: You can also start Firefox in Troubleshoot 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 Continue in Safe ModeStart in Safe Mode.
  3. Check whether your problem is still happening while in Safe Mode.


4. Troubleshoot your plugins

Sometimes plugins for Firefox (such as Adobe Reader, Flash, Java, QuickTime, RealPlayer, and Windows Media Player) can cause problems that may be fixed in the latest version. To check to see if you have the latest versions of all your plugins, go to our Plugin Check page If any of your plugins are out of date, click Update and follow the instructions for updating that plugin. After you've updated all of your plugins, restart Firefox: The template "closefirefox" does not exist or has no approved revision. 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. Click the menu button Fx89menuButton, click Add-ons and themes and select Plugins.
  2. Click each plugin in the list and then click Disable.
  3. Check whether your problem happens when you have all plugins disabled.

If your problem goes away when all of 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 which one is causing it.


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.

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/firefox.
  2. Exit Firefox: The template "closefirefox" does not exist or has no approved revision.
  3. Delete the Firefox installation folder, which is located in one of these locations, by default:
    • (32-bit Windows) C:\Program Files\Mozilla Firefox
    • (64-bit Windows) C:\Program Files (x86)\Mozilla Firefox
  4. Reinstall Firefox - see How to install Firefox on Windows for instructions.
  1. Download the latest official version of Firefox from mozilla.org/firefox.
  2. Quit Firefox: The template "closefirefox" does not exist or has no approved revision.
  3. Uninstall Firefox 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/firefox.
  2. Quit Firefox: The template "closefirefox" does not exist or has no approved revision.
  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 has, you can reinstall the extensions and themes you verified (in part 4 above) were not causing problems. If your problem hasn't been fixed continue with the next troubleshooting method.

6. Reset Firefox

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

Note: When you refresh Firefox, 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 Fx89menuButton, click Help and select More Troubleshooting Information.
  2. Click Refresh Firefox… then Refresh Firefox in the confirmation window that opens. Firefox will close to refresh itself.
  3. When finished, a window will list your imported information. Click the Finish button. Firefox will open.
  4. Select whether you want Firefox to restore all or some windows and tabs and click the Let's go! button.
Note: There's a Refresh Firefox button in the Firefox Troubleshoot 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.

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. Click the menu button Fx89menuButton to open the menu panel.
  2. Click History and select Clear Recent History…
  3. In the Time Range to clear: drop-down, select Everything.
  4. Below the drop-down menu, select both Cookies and Cache. Make sure other items you want to keep are not selected.
  5. Click OKClear Now.
For more information, see Delete browsing, search and download history on Firefox.


3. Restart Firefox in Safe Mode

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. Click the menu button Fx89menuButton, click Help, select Troubleshoot Mode… and click Restart in the Restart Firefox in Troubleshoot Mode? dialog.

    Note: You can also start Firefox in Troubleshoot 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 Continue in Safe Mode.
  3. Check whether your problem is still happening while in Safe Mode.

4. Troubleshoot your plugins

Sometimes plugins for Firefox (such as Adobe Reader, Flash, Java, QuickTime, RealPlayer, and Windows Media Player) can cause problems that may be fixed in the latest version. To check to see if you have the latest versions of all your plugins, go to our Plugin Check page If any of your plugins are out of date, click Update and follow the instructions for updating that plugin. After you've updated all of your plugins, restart Firefox: The template "closefirefox" does not exist or has no approved revision. 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. Click the menu button Fx89menuButton, click Add-ons and themes and select Plugins.
  2. Click each plugin in the list and then click Disable.
  3. Check whether your problem happens when you have all plugins disabled.

If your problem goes away when all of 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 which one is causing it.


5. Reset your Firefox settings

Some problems can be fixed by resetting your Firefox preference settings:

  1. Click the menu button Fx89menuButton, click Help, select Troubleshoot Mode… and click Restart in the Restart Firefox in Troubleshoot Mode? dialog.

    Note: You can also start Firefox in Troubleshoot 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 to put a check mark by Reset all user preferences to Firefox defaults.
  3. To apply your changes, click Make Changes and Restart.

6. 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.

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/firefox.
  2. Exit Firefox: The template "closefirefox" does not exist or has no approved revision.
  3. Delete the Firefox installation folder which is located here by default:
    • (32-bit Windows) C:\Program Files\Mozilla Firefox
    • (64-bit Windows) C:\Program Files (x86)\Mozilla Firefox
  4. Reinstall Firefox - see How to install Firefox on Windows for instructions.
  1. Download the latest official version of Firefox from mozilla.org/firefox.
  2. Quit Firefox: The template "closefirefox" does not exist or has no approved revision.
  3. Uninstall Firefox 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/firefox.
  2. Quit Firefox: The template "closefirefox" does not exist or has no approved revision.
  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 has, you can reinstall the extensions and themes you verified (in part 4 above) were not causing problems. If your problem hasn't been fixed continue with the next troubleshooting method.

7. Make a new profile

A bad profile can cause all kinds of problems with Firefox. To see whether your problem is caused by a bad profile, make a new one. If that fixes the problem, you can copy your data (bookmarks, saved passwords, etc.) over to the new profile.

  1. Use the instructions in the Profile Manager - Create, remove or switch Firefox profiles article to start the Profile Manager and create a new profile.
    When creating a new profile, do not delete your old profile. You will lose all of your bookmarks, history, passwords and settings.
  2. Once you've created a new profile, select it in the Profile Manager and click Start Firefox.

Test to see if your problem occurs with the new profile. If it doesn't, you can copy your data to the new profile - see Recovering important data from an old profile 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 services are often useful:

For more tools, 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)