Troubleshooting extensions and themes

Some problems with Firefox are caused by extensions, themes or hardware acceleration. This article will help you determine whether one of these is causing your problem and, if it is, describe how to make Firefox run normally again.

Start Firefox in Safe Mode

When you start in Firefox's Safe Mode, all extensions are temporarily disabled, hardware acceleration is turned off and the default theme is used. This will help determine whether one of these is causing your problem.

1. At the top of the Firefox window, click the Firefox button, go over to the Help menu and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.
   For Windows XP, click the Help menu and select Restart with Add-ons Disabled....

   Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.
2. When the Firefox Safe Mode window appears, press the button Continue in Safe Mode.

After Firefox starts in Safe Mode, test for your problem.

The problem still occurs in Safe Mode

If your problem persists in Safe Mode, it is not being caused by an extension, theme or hardware acceleration.Other possible causes could be plugins or changes made to Firefox preference settings, which are not disabled in Safe Mode.

• For additional troubleshooting suggestions, see Basic Troubleshooting, Troubleshooting plugins, and Resetting preferences.

The problem does not occur in Safe Mode

If your problem did not occur in Safe Mode, it is most likely because of an extension, theme or hardware acceleration. Continue following the steps in this article to determine the cause of your problem.

Turn off hardware acceleration

With some graphics card and graphics driver setups, Firefox may crash or have trouble showing text or objects on pages when using hardware acceleration. You can try turning off hardware acceleration to see if it fixes the problem.

1. At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP) and then clickOptions
2. Select the Advanced panel and the General tab.
3. Uncheck Use hardware acceleration when available.
4. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then clickExit.
5. Start Firefox the way you normally do.

If the problem is no longer happening, then hardware acceleration was likely the cause. You can try updating your graphics drivers to see if that fixes it or simply run without hardware acceleration. Otherwise, your problem is likely related to extensions or themes. Continue with the steps in this article to see if they help.

Switch to the default theme

If you are using a theme other than the default Firefox theme:

1. At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP), and then clickAdd-ons. The Add-ons Manager tab will open.
2. In the Add-ons Manager tab, select the Appearance panel.
3. Select the default theme, then click the Enable button, to make Firefox switch to that theme.
4. Click Restart Firefox if necessary.

After you restart Firefox, test for your problem. If it no longer occurs, the theme you were using was causing it. If it still occurs, continue following the steps in this article.

Disable all extensions

To determine whether a faulty extension is causing your problem, you can disable all of your installed extensions:

1. At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP), and then clickAdd-ons. The Add-ons Manager tab will open.
2. In the Add-ons Manager tab, select the Extensions panel.
3. Click the name of an extension in the list to select it.
4. Click Disable to disable the selected extension.
5. Repeat this for each of the other extensions in the list.
6. Click Restart Firefox.

After you restart Firefox, all extensions will be disabled. Test for your problem.

• If the problem still occurs with all extensions disabled, it is most likely that the localstore.rdf file in your Firefox profile is corrupt. You can Reset toolbars and controls to resolve the problem.

If the problem no longer occurs with all extensions disabled, one of your extensions was causing it. To find the extension that was causing your problem, continue as follows:

Test for faulty extensions

To determine which of your disabled extensions was causing your problem, you can re-enable each extension one at a time.

1. At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP), and then clickAdd-ons. The Add-ons Manager tab will open.
2. In the Add-ons Manager tab, select the Extensions panel.
3. Click the name of an extension in the list to select it.
4. Click Enable to enable the selected extension.
5. Click Restart Firefox.

After you restart Firefox, test for your problem. If the problem comes back, the extension you just enabled was causing it.

Note: If you have a large number of extensions, it may be quicker to enable more than one extension at a time. The method with the fewest number of restarts required is: Enable half the extensions in this list, then restart Firefox and test for the problem. If the problem reoccurs, you know that the faulty extension is one of the ones you just enabled. If the problem does not occur, you know the faulty extension is one of the disabled ones. Repeat the process until the faulty extension is found.

After you find the extension that was causing your problem, disable or uninstall the faulty extension and re-enable the other extensions in the Add-ons window.

Updating extensions

If an extension was causing your problem, it may have an update available that will fix it:

1. At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP), and then clickAdd-ons. The Add-ons Manager tab will open.
2. In the Add-ons Manager tab, select the Extensions panel.
3. Click Find Updates.
4. If updates are found, install them by clicking Install Updates.
5. When the installation is complete, click Restart Firefox.

After Firefox restarts, your extensions will be updated. If the extension that was causing your problem had an update, re-enable it and test for your problem again.