Firefox Will Not Open - Troubleshooting Tips

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The Firefox web browser displays websites quickly, and it has a minimalist user interface. Users can customize the browser as they like with themes, add-ons and extensions. Sometimes, Firefox has trouble displaying websites, and it may even crash. A particularly annoying part of using Firefox is that on occasion, it fails to even start up. Double-clicking the Firefox icon not once, but multiple times results in error messages, or worse: no response at all. There could be several reasons for this, including the fact that Firefox may not have closed properly when it was used previously, or the various extensions could have disrupted the normal functioning of the web browser. Whatever the case may be, there are ways to solve the problem and get Firefox back up and running.

Firefox Doesn’t Open

Upon double-clicking the Firefox icon, a browser window should open and display your home page. If this does not happen and there are not any error messages that pop up, another program running on the computer may be interfering with the web browser. Close any programs that are open and try launching Firefox again. If this does not work, restart the computer and open Firefox. If you still are not having any luck, there are other things to consider.

Firefox Process Running in Background

Usually, if Firefox will not open after double clicking the icon, a message box pops up and explains that Firefox is still running. This probably means that the web browser did not properly close the last time it was used. To address this problem, any Firefox processes that are currently running must be ended. Follow these steps to perform this task:

  • Right-click on the task bar and select Task Manager.
  • In the Task Manager, click the Processes tab
  • Locate the Firefox process by pressing the ‘F’ key. It will appear as firefox.exe.
  • Right-click on the firefox.exe process and select End Process.
  • If a warning message pops up, click Yes.
  • Close the Task Manager.

One of the reasons why Firefox may not close properly is that certain extensions in the browser are conflicting. Namely, Norton Antivirus software and Skype are known to have problems with Firefox. To address this, disable these extensions (if you have them installed) by following these steps:

  • Start Firefox, go to Tools in the menu bar and select Add-ons.
  • Click the Extensions Tab.
  • Select Norton IPS, Norton Toolbar and Skype and for each one, click Disable.
  • Close Firefox and re-open.

Opening FireFox in Administration Mode

Another reason why Firefox may not open is that it requires an administrator login. This may be the case if the computer has multiple user accounts and some of the accessibility has been denied to some users. To use Firefox as an administrator in Windows XP, right-click on the firefox.exe file in the Firefox program folder and select Run As. Then, go to The Following User, under the User Name drop down box, and select Administrator. Enter the password and click OK. For Windows 7 or Vista, choose Run as Administrator after right-clicking the file. The option should also be available if you right-click the Firefox icon on the desktop.

Themes or Extensions Preventing Firefox From Opening

If a theme or extension is preventing Firefox from opening, opening the web browser in Safe Mode is the best way to see if this is the case. In Safe Mode, all extensions are disabled and the default theme is applied. To start Firefox in Safe Mode, follow these steps:

  • Exit Firefox.
  • Open the Start menu and expand the All Programs list.
  • Find the Mozilla Firefox folder and select Mozilla Firefox (Safe Mode).
  • In the Firefox safe mode window, select Continue in Safe Mode.

If the web browser still does not work, then something else is wrong. If Firefox works properly in safe mode, then an extension or the theme is causing the problem. Test whether the theme is the cause of the problem. Go to Tools, select Add-ons and click the Appearance (or Theme) panel. Select the default theme and click Use Theme. Restart Firefox. If it works, then the previous theme was causing the problem. If Firefox is not working, check the extensions.

Start by disabling all the extensions and restarting Firefox. If Firefox still is not working, something else is causing the problem. If Firefox works fine, then one of the extensions is the problem. Enable one extension at a time and restart Firefox. This will help you find the extension that is causing the problem.

Connection Errors

Another area to consider is connection issues. This usually prompts an error message when Firefox is launched, such as “unable to connect” or “server not found.” Check your internet connection to see that the cables are secure. If you are connected wirelessly, check that the signal is strong. Turning the router off for a minute and then turning it back on may fix some connection problems.