How to fix the Update Failed error message when updating Firefox

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Firefox includes a Software Update feature that automatically checks for updates and prompts you to install them when necessary. For more information about the Software Update feature, see Update Firefox to the latest release.

Sometimes, the updater fails and displays the following error message:

Software Update Failed
The update could not be installed. Please make sure there are no other copies of Firefox running on your computer, and then restart Firefox to try again.

This article presents possible solutions to this problem and workarounds to get Firefox updated.

Another application is using Firefox

Close ALL other programs and attempt to restart Firefox. Some e-mail programs (such as Eudora) can have processes reserved in Firefox with no outward indication.

Another user is running Firefox

If you share your computer with other users, and another user's account is still logged in with Firefox running, this error can occur. Make sure you're the only user logged in to the computer when updating Firefox. The easiest way to do this is to restart your computer. Once the computer starts up again:

  1. Start Firefox,
  2. At the top of the Firefox windowOn the menu bar, click on the Help menuFirefox button, go over to the Help menu (on Windows XP, click on the Help menu)Help menu and select About FirefoxCheck for Updates....

End all Firefox processes and restart Firefox

End any Firefox processes that may still be active, either manually or by restarting your computer.

You can manually end the Firefox process using Windows Task Manager.

  1. Right-click on an empty spot in the Windows task bar and select Task Manager (or press Ctrl+Shift+Esc).
  2. Select the Processes tab.
  3. Select the firefox.exe entry in the processes list, click End Process and click Yes in the "Task Manager Warning" dialog that appears.

Once all instances of Firefox have been ended or after the computer starts up again, restart Firefox to see if the updater is now working.

Run as Administrator

If you are using Windows 7 or Vista:

  1. End the Firefox process in Windows Task Manager as explained above, or reboot the computer so that no Firefox processes are active.
  2. Open the Windows Start Menu, type firefox and right-click on the "Mozilla Firefox" entry that appears.
  3. Select Run as Administrator and Continue if the User Account Control dialog comes up.

If the issue is not resolved, end Firefox again, as explained above, but this time, open the C:\Program Files\Mozilla Firefox folder, right-click on the firefox or firefox.exe file icon and select Run as Administrator.

Spybot TeaTimer

Spybot TeaTimer can interfere with Firefox updates. If you use Spybot, try disabling TeaTimer before updating Firefox.

  1. Open Spybot
  2. Open Mode and choose Advanced
  3. In the prompt that comes up, press OK.
  4. Click Tools, then Resident.
  5. Uncheck Resident "TeaTimer".

Now that TeaTimer is off, try updating Firefox again by clicking the Help menu, and selecting Check for Updates....

Regardless of whether Firefox can now update, remember to re-activate TeaTimer.

Logitech QuickCam

If you use a Logitech Web camera, the QuickCam software can interfere with Firefox updates. Physically disconnect the camera from your computer. If you have a QuickCam icon in the Windows system tray, right-click the icon and select "Exit".

If you do not see a QuickCam icon, you stop the software from running using Windows Task Manager, as follows:

  1. Right-click on an empty spot in the Windows task bar and select Task Manager (or press Ctrl+Shift+Esc). The Windows Task Manager will open.
  2. Click the Processes tab.
  3. Select the "Quickcam.exe" entry in the processes list and click End Process
  4. Click Yes in the Task Manager Warning dialog.

With Quickcam no longer running, try updating Firefox again by clicking the Help menu, and selecting Check for Updates....

XULRunner Programs

XULRunner programs (e.g. Azureus Vuze) will use parts of Firefox. Close other programs, then try updating Firefox again.

Last resort

If you have tried every solution above and you still see the Software Update Failed message, you can update Firefox by installing the new version over top of your current version. See Installing Firefox for details. If you are seeing this error even though you have installed the latest version of Firefox, see Updates reported when running newest version.

Based on information from Software Update (mozillaZine KB)