Troubleshoot and diagnose Firefox problems (2024)

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.

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

Many problems with loading web pages can be resolved by clearing Firefox's cookies and cached Web content. To learn more, see Clear cookies and site data in Firefox and How to clear the Firefox cache.

To clear cookies and cache all at once:

Firefox also has a startup cache that stores certain temporary data, to improve startup speed. Clearing the startup cache and then restarting Firefox can resolve various issues with the Firefox user interface (UI). This will not change your profile data or add-ons.

1. Click the menu button , click Help and select More Troubleshooting Information. The Troubleshooting Information page will open.
2. Under Try clearing the startup cache, click Clear startup cache… and then click Restart.

Firefox Troubleshoot Mode is a diagnostic mode that disables extensions, uses the default theme, turns off hardware acceleration and uses default toolbar settings, among other changes (see this article for details). To start Firefox in Troubleshoot Mode:

1. Click the menu button , 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 next Open Firefox in Troubleshoot Mode? dialog, click Open.
3. Check whether your problem is still happening while in Troubleshoot Mode.

• If the problem still happens in Troubleshoot Mode, go on to step 4.
• If the problem does not happen in Troubleshoot Mode, follow these instructions to troubleshoot extensions, themes, and hardware acceleration.

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.

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

If you have many Firefox customizations, you may want to skip this step and create a new Firefox profile instead (see step 6, below) so that your old profile is easily recoverable from the Profile Manager.

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 , 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.

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 the Profile Manager - Create, remove or switch Firefox profiles article for instructions.

If you've tried all of these troubleshooting methods, and you're still having problems, here are some other solutions you can try:

Check browser internals

The Firefox Task Manager (about:performanceabout:processes page) lets you see whether tabs or extensions are slowing down Firefox. Telemetry Data shared with Mozilla (about:telemetry page) contains detailed data about performance, hardware, usage, and customization. The Troubleshooting Information page (about:support page) includes other about: page links and troubleshooting resources. (For a list of all about: pages, enter about:about in the address bar.)

Check for malware

Malware (short for “malicious software”) can cause problems with Firefox. Periodically, you should scan your system for viruses, spyware, or other malware. For more information, see Troubleshoot Firefox issues caused by malware.