"Firefox is already running but is not responding" error message - How to fix it

All of your personal settings, bookmarks, and other information are kept in your Firefox profile. To start, Firefox needs an unlocked profile and if it is not the case, it displays the "Firefox is already running, but is not responding" message. This article explains how to prevent this message from showing at startup.

Note: If this is a recurring problem, see Firefox hangs when you quit it for possible causes and solutions.

Table of Contents

• End Firefox processes
• Remove the profile lock file
• Check the profile folder name and location
• Initialize the connection to a file share
• Check access rights
• Restore data from a locked profile

End Firefox processes

If Firefox did not shut down normally when you last used it, Firefox might still be running in the background, even though it is not visible. Restart your computer to see if the problem goes away.

Instead of restarting your computer, you can also close Firefox in linux ubuntu, as follows:

1. Click on system and choose administration.
2. In administration, click on system monitor. Here you will find firefox-bin one or more times.
3. Highlight the listing and click the "end process" for each one.

Instead of restarting your computer, you can also use the Windows Task Manager to close the existing Firefox process:

1. Right-click on an empty spot in the Windows task bar and select Task Manager (or press Ctrl+Shift+Esc).
2. When the Windows Task Manager opens, select the Processes tab.
   
   
   
3. Select the entry for firefox.exe (press F on the keyboard to find it) and click End Process.
4. Click Yes in the "Task Manager Warning" dialog that appears.
5. Repeat the above steps to end any additional firefox.exe processes, if more than one entry is found, then exit the Windows Task Manager.
6. Start Firefox normally.

"Firefox is already running but is not responding" error message - How to fix it

Adobe Flash plugin has crashed - Prevent it from happening again

The message The Adobe Flash plugin has crashed is shown when the Flash plugin stops working unexpectedly. Simply reload the page to restart the plugin and show the video (or game, animation, etc.) again.

Firefox runs plugins like Flash in a separate process (see What is plugin-container). This is done to prevent Firefox from crashing when a plugin stops working. This article covers what you can do to avoid Flash plugin crashes.

 

Adobe Flash plugin has crashed - Prevent it from happening again

Adobe Flash Player 11.3 for Mozilla Firefox crashes

Adobe Flash Player for Mozilla Firefox 11.3 crashes more frequently than previous versions of Flash. Updating to the latest version of Flash should fix this issue for most people.

Note: This article only applies to Windows and Mac.

Note: This article is specifically for crashes with Flash 11.3. If you are experiencing issues with Flash 11.3 such as video appearing black, white or grey and never playing, please see Flash 11.3 doesn't load video in Firefox.

Table of Contents

• Solution 1: Update Flash
  
• Solution 2: Downgrade to Flash 10.3
  
  • Step 1: Uninstall Flash
    
  • Step 2: Install Flash 10.3
    

Solution 1: Update Flash

1. Go to the Flash Player download page at Adobe.com and download the Flash installer.
   
   Caution: Adobe's download page may include a checkbox for optional software (such as Google Chrome or McAfee Security Scan) that is selected by default. If you do not clear the checkbox before downloading, that software will be installed on your computer when you open the Flash installer.
2. When the download has finished, close Firefox. At the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
   At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit
3. Open the Flash installer file you downloaded and follow the instructions.
   

Note: If you are having problems with the Flash installer from Adobe's download page, you can download the full Flash Player installer directly from Adobe.com.

1. Go to the Flash Player download page at Adobe.com and download the Flash installer.
   Note: The latest Flash player no longer supports PPC Macs. Instead, use Flash 10.1.102.64 which can be found in this archive
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Open the file you downloaded (e.g install_flash_player_osx_intel.dmg or flashplayer10_1r102_64_ub_mac.dmg).
4. In the Finder, open the Install Adobe Flash Player.app to run the installer, then follow the installer's instructions.

1. Go to the Flash Player download page at Adobe.com and download the Flash installer.
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Open the file you downloaded (i.e. install_flash_player_osx_intel.dmg).
4. In the Finder, open the Install Adobe Flash Player.app to run the installer, then follow the installer's instructions.

1. Go to the Flash Player download page at Adobe.com.
2. When prompted, save the file (i.e. install_flash_player_"version"_linux."processor".tar.gz).
3. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
4. Open a Terminal window (in Gnome, click on the Applications menu, select Accessories, and then select Terminal.)
5. In the Terminal window, change to the directory where you saved the file you downloaded (e.g. cd /home/user/Downloads).
6. Extract libflashplayer.so from the file you downloaded with the command tar -zxvf install_flash_player_"version"_linux."processor".tar.gz.
7. As the super user, copy the extracted file, libflashplayer.so, to your Firefox installation directory's plugins sub-directory. For example, if Firefox is installed in /usr/lib/mozilla, use the command sudo cp libflashplayer.so /usr/lib/mozilla/plugins and then enter your super user password when prompted.
   
   

Solution 2: Downgrade to Flash 10.3

If updating Flash to the latest version didn't solve the problem, you can try downgrading to Flash 10.3.

Warning: Flash 10.3 doesn't auto-update so you won't be notified of new versions. Keeping Flash up to date is critical to keeping your computer safe.

Note: You may want to write down these steps or print them out as you will have to close Firefox during this process.

Step 1: Uninstall Flash

To uninstall Flash on Windows, you will need to use the uninstaller provided by Adobe.

1. Download the uninstaller program from Adobe - uninstall_flash_player.exe (671 KB)
   
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit At the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
   
3. Run the uninstall Flash program that you download and follow the prompts.
   
4. When you are finished, start Firefox again and continue with the next section.
   

See the Adobe help article Uninstalling Flash Player on Windows for more details.

Step 2: Install Flash 10.3

The following instructions will show you how to download and install Flash 10.3.

1. Download Flash 10.3 from the Adobe site - install_flash_player_10_plugin.exe
   
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit At the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
   
3. Open your downloads folder and double-click the file named install_flash_player_10_plugin.exe to start the installation.
   
4. Follow the instructions in the installer. When the installation is complete you can open Firefox again.
   

Solution 1: Update Flash

1. Go to the Flash Player download page at Adobe.com and download the Flash installer.
   Caution: Adobe's download page may include a checkbox for optional software (such as Google Chrome or McAfee Security Scan) that is selected by default. If you do not clear the checkbox before downloading, that software will be installed on your computer when you open the Flash installer.
2. When the download has finished, close Firefox. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Open the Flash installer file you downloaded and follow the instructions.

Note: If you are having problems with the Flash installer from Adobe's download page, you can download the full Flash Player installer directly from Adobe.com.

1. Go to the Flash Player download page at Adobe.com and download the Flash installer.
   Note: The latest Flash player no longer supports PPC Macs. Instead, use Flash 10.1.102.64 which can be found in this archive
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Open the file you downloaded (e.g install_flash_player_osx_intel.dmg or flashplayer10_1r102_64_ub_mac.dmg).
4. In the Finder, open the Install Adobe Flash Player.app to run the installer, then follow the installer's instructions.

1. Go to the Flash Player download page at Adobe.com and download the Flash installer.
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Open the file you downloaded (i.e. install_flash_player_osx_intel.dmg).
4. In the Finder, open the Install Adobe Flash Player.app to run the installer, then follow the installer's instructions.

1. Go to the Flash Player download page at Adobe.com.
2. When prompted, save the file (i.e. install_flash_player_"version"_linux."processor".tar.gz).
3. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
4. Open a Terminal window (in Gnome, click on the Applications menu, select Accessories, and then select Terminal.)
5. In the Terminal window, change to the directory where you saved the file you downloaded (e.g. cd /home/user/Downloads).
6. Extract libflashplayer.so from the file you downloaded with the command tar -zxvf install_flash_player_"version"_linux."processor".tar.gz.
7. As the super user, copy the extracted file, libflashplayer.so, to your Firefox installation directory's plugins sub-directory. For example, if Firefox is installed in /usr/lib/mozilla, use the command sudo cp libflashplayer.so /usr/lib/mozilla/plugins and then enter your super user password when prompted.
   
   

Solution 2: Downgrade to Flash 10.3

If updating Flash to the latest version didn't solve the problem, you can try downgrading to Flash 10.3.

Warning: Flash 10.3 doesn't auto-update so you won't be notified of new versions. Keeping Flash up to date is critical to keeping your computer safe.

Note: You may want to write down these steps or print them out as you will have to close Firefox during this process.

Step 1: Uninstall Flash

To uninstall Flash 11.3 on Mac OSX, you will need to use the uninstaller provided by Adobe.

1. Download the uninstaller program from Adobe:
   • Mac OS X, version 10.6 and 10.7: uninstall_flash_player_osx.dmg (225 KB)
   • Mac OS X, version 10.5: uninstall_flash_player_osx.dmg (225 KB)
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Double-click the .dmg file that you downloaded to open a folder with the uninstall Flash program.
4. Double-click the uninstall Flash program and follow the prompts.
5. When you are finished, start Firefox again and continue with the next section.

See the Adobe help article Uninstalling Flash Player on Mac OS for more details.

Step 2: Install Flash 10.3

The following instructions will show you how to download and install Flash 10.3.

1. Download Flash 10.3 from the Adobe site - install_flash_player_10_osx.dmg
2. At the top of the Firefox window, click on the Firefox button (File menu in Windows XP) and then click ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select QuitAt the top of the Firefox window, click on the File menu and select ExitOn the menu bar, click on the Firefox menu and select Quit FirefoxAt the top of the Firefox window, click on the File menu and select Quit.
3. Open your downloads folder and double-click the file named install_flash_player_10_osx.dmg to open a folder with the Flash 10.3 install program.
4. Double-click the Flash 10.3 installer to start the installation.
5. Follow the instructions in the installer. When the installation is complete you can open Firefox again.

Share this article: You can use the link http://mzl.la/LdjZH6 to easily share this article with others. It will display instructions automatically customized for their operating system and language.

Adobe Flash Player 11.3 for Mozilla Firefox crashes

Mozilla Firefox crashing - 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 click Add-onsOn the menu bar, click on the Tools menu, and then click Add-onsAt the top of the Firefox window, click on the Tools menu, and then click Add-ons. The Add-ons Manager tab will openAt the top of the Firefox window, click on the Tools menu, and select Add-onsOn the menu bar, click on the Tools menu, and select Add-onsAt the top of the Firefox window, click on the Tools menu, and select Add-ons. The Add-ons window will open.
   
2. In the Add-ons window, select the Extensions panel.
   Manager tab
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.

Mozilla Firefox crashing - Test for faulty extensions