Diagnose Firefox issues using Troubleshoot Mode

Troubleshoot Mode runs Firefox with some features and customizations disabled (see below for details). If you're having a problem in Firefox that does not occur in Troubleshoot Mode, the cause of the problem is one of the disabled items.

How to start Firefox in Troubleshoot Mode

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).

Troubleshoot Mode window


You will have two options:

  • Clicking the Open button will start Firefox with the default theme, your extensions will be disabled, and some other features and customizations will be turned off. These changes are temporary. When you leave Troubleshoot Mode and start Firefox normally, your add-ons and other settings will return to the state they were in before you entered Troubleshoot Mode.
  • Clicking the Refresh Firefox button will restore Firefox to its factory default state while saving your essential information. These changes are permanent. See Refresh Firefox - reset add-ons and settings for more information, before you choose this option.

Diagnosing problems in Troubleshoot Mode

After you start Firefox in Troubleshoot Mode, you'll want to test its behavior and see if the problem goes away.

The problem happens in Troubleshoot Mode

If the problem still happens in Troubleshoot Mode, it is not being caused by an extension or theme. Other possible causes include changes made to Firefox preference settings, which are not disabled in Troubleshoot Mode. See the following articles for solutions:

The problem does not happen in Troubleshoot Mode

If the problem does not happen in Troubleshoot Mode, the most likely cause is an extension, theme or hardware acceleration. See this article for solutions:

Exiting Troubleshoot Mode

  1. Click the Firefox menu Fx89menuButton and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu Fx89menuButton and select Quit.
  2. Start Firefox as you normally would.

What does Troubleshoot Mode disable?

Based on information from Safe mode (mozillaZine KB)

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