This has got to be one of the most annoying errors associated with the popular web browser Mozilla FireFox. If FF encounters a problem when an update is being applied, an error message "Software Update Failed. The update could not be installed…” will be displayed every time you try to start the application. I was unfortunate enough to face the issue myself and luckily managed to solve it wihout having to waste a lots of time. If you are encountering the same issue, here are a few things you can try to hopefully get the problem sorted out.

FireFox 3.5 logo

Note: Before you try any of the fixes below please backup your personal settings, bookmarks and saved passwords.

  1. Browse to Start Menu –> Programs –> Mozilla FireFox and right click the FireFox shortcut. Choose ‘run as administrator’ from the menu and execute. If it doesn’t work the first time, try 2-3 times. If FF cannot update due to insufficient user account privileges this should solve it.
  2. Browse to C:\Users\USERNAME\AppData\Local\Mozilla\FireFox\Mozilla FireFox (path is different in Windows XP). Delete the updates directory, updates.xml and active-update.xml files if they are present. Start FireFox. If FF encountered an error during the update process, this should clear the last update and start fresh from the beginning.
  3. If it still doesn’t work, go to Mozilla download page and download the latest version of FireFox. Without uninstalling the existing version, execute the new setup. If the existing version is 3.X/3.5.X, newest version will be installed over the existing installation, clearing any update mishaps.

Good Luck!


  1. Alex Gold // 6/04/2014 04:53:00 AM  

    Wonderful program to browse Web sites Thank you for providing the program If you are facing problem with your Mozilla Firefox support, You can reach Acetecsupport at their Toll Free No +1-800-231-4635 For US/CA.