I think man you should go for a clean install than upgrading, since you are very back.

Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

Thank you.

Hi anushbmx Yes, I now have version 25.0.1 and it appears to be fine. Of course, I still can't tell why the automatic updates stopped working 15 months ago and so I don't know whether they will happen properly now. Any thoughts?

Are you an admin user on your machine? Or do you have any anti-virus that would have prevented software installations from taking place?

Hello Tylerdowner

Yes, I am an Administrator user although I normally log on as an ordinary user as a security precaution. I run McAfee Internet Security as my anti-virus which hasn't changed and I am unaware of any previous updating difficulties caused by this. It occurs to me that I switched to Windows 7 around the time the upgrading seems to have stopped. I can't be sure of exact timings and I don't know if it might be relevant or not?

Firefox won't update as an ordinary user, you need to be an admin user (though after Firefox 26 ordinary users can update Firefox as well). So that's likely the issue.

Hi Thank you. That would explain it. When I migrated to Windows 7 was also when I first set up a separate Administrator account with an ordinary account for 'day-to-day' use. Which is when auto-updating seems to have stopped! Thanks again.