Firefox is Already Running Error Message

A common error message that is encountered when using Firefox is:

“Firefox is already running but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.”

This error message will appear when a Firefox is initially being started, and it can be caused by a number of different reasons, including:

• Firefox did not shut down properly the last time it was used,
• The Firefox profile folder cannot be found or accessed by Firefox, and
• There is an issue with access rights available for Firefox.

Each of these issues can cause the Firefox is already running error to be displayed when a new instance of Firefox is attempted to be launched. Unfortunately, the error message is always the same, so there is no way of knowing which issue is causing the problem. As such, each fix will have to be worked through until the error is corrected. Profiles and access rights will be addressed in the future.

Using Task Manager to Close Firefox

If Firefox did not close properly the last time you used it, you can either restart your system or use Windows Task Manager to correct the problem.

In most cases, when you open Task Manager (Ctrl+Alt+Del), you will not see an instance of Firefox running in the Applications tab. Instead, you will have to go to the Processes tab and close Firefox from there. Scroll down through the processes until you find firefox.exe. Click it to highlight it and then click the End Process button. Do this for all entries you find.

You should now be able to start Firefox normally.

Restarting Windows to Close Firefox

In some cases, even though you closed Firefox, it may still be running in the background (due to an error on closing). You can close all background applications by shutting down and restarting your system. If it is running in the background, you may receive an error when the computer is trying to close asking if you want to shut down the program.

When your computer starts up again, you should be able to start Firefox as normal.

Firefox Unresponsive Script Warnings

Firefox is a web browser designed by Mozilla and is an alternative to Microsoft Internet Explorer. When using Firefox, you may receive an error message that states Warning: Unresponsive script or a script on this page may be busy or it may have stopped responding. A script is the set of instructions that provide a program with the directions to carry out a task. An unresponsive script is one that cannot move to action to carry out the command being asked of it.

Usually, Firefox generates these types of error messages because it thinks a script may be running out of control, or the web page you are trying to access is not working. Whatever the reason for the unresponsive script warning, there are a number of things that can be done to rectify the situation.

First, you can let the script run and see if it corrects itself. You can choose to click the Continue button, which will allow the script to keep running. Over time, it may finish running and the web page will begin working again. Unfortunately, this is not always the case and clicking the Continue button may just bring up the same error message again. If the Continue button does not work out the error, take the following steps to increase the length of time you allow the script to run:

• In the address bar, type about:config and press Enter.
• A warning message that states “This might void your warranty!” may pop up. If this comes up, click the “I’ll be careful, I promise!” button.
• You will be sent to the about:config page. Search the available options for the dom.max_script_run_time. You can type the preference name in the Filter: box to speed up the process.
• Double click on this preference.
• Change the 10 to a 20 and click the OK button. This will increase the amount of time the script is able to run in the hopes that it will have enough time to fix the error by itself.

If you have noticed that you only receive unresponsive script warnings when accessing certain websites, blocking these scripts from running on those sites will solve the problem.

• Do an Internet search for the Firefox YesScript extension and download it.
• Install YesScript as an add-on by following the prompts that will walk you through the download process.
• Restart Firefox.
• Open the Firefox window and click Tools.
• Select Add-ons from this menu.
• Click Options.
• In the YesScript Blacklist box, type the URL of the site where you are having script error problems.
• Click Add.

By completing the above steps, YesScript will block the site from running script errors when you are on it.