You can manually reset the Software Update feature by closing Firefox and deleting the "updates" folder (which you seems to have done) and the two files "active-update.xml" and "updates.xml" - these are either in the installation directory (C:\Program Files\Mozilla Firefox) or in the profile folder (C:\Documents and Settings\username\Application Data\Mozilla\Firefox\Profiles\something.default).

If this does not help, please see our KB article How to fix the Update Failed error message when updating Firefox - the 'Last resort' section may be useful, or or check out this MozillaZine KB article, Software Update.

Please let us know how above works out, and if we can be of further assistance.

Try this: Close Firefox Rename C:\Program Files\Mozilla Firefox\updates.xml to updates.xml.bak

To AlleyKat and Chris_Ilias:

Thanks very much for your help in solving my problem, and for providing it so quickly.

In my case, the following procedure replaces "Apply Downloaded Update Now" with "Check for Updates" in the Help menu when the update fails because the downloaded update files are missing.

1. Close Firefox.

2. In Windows Explorer, navigate to the Firefox installation folder, e.g. "C:\Program Files\Mozilla".

3. In that folder, delete or rename the "active-update.xml" file.

If possible, please mark Chris' answer as 'solved my problem' - this will in the future help other FF users with the same problem find the solution easier. ;-)

in Windows 7 or Windows Vista you choose "show all files and folders" and delete under \Users\{loginname}\AppData\Mozilla the folder Firefox. This has solved my problem.

I found an easy fix for the problem of the "Apply Downloaded Update Now.." in the "Help" pull-down menu. I noticed that Firefox in my "Administrator" account did not have the "Apply Downloaded Update Now..." problem. I temporarily changed my user account to have administrator privileges, saved it, and then reset it to "Standard" access. I then checked my User account, and Firefox finally read "Check for Updates" in the "Help" menu, as it should. I also don't get a dialogue box trying to install an older update than what is currently installed any longer either.

When I went back into my "User" account, everything was fixed and running perfectly. I hope this works for you as easily as it worked for me. It took me all of 30 seconds, and I didn't have to move, rename, or delete any files or folders. That's the way it should be. Playing around with deleting and / or moving files and folders is a sure way to generate more problems down the road. Good luck! bcheprenpe.

this worked for me as well after trying many unsuccessful things(several hrs.) of it. Thanks to bcheprenpe.

The following dos commands fixed this problem for me on windows xp with firefox 3.6.X

Kill firefox

taskkill /f /t /IM "firefox.exe"

Remove the necessary dir and files

rmdir /S /Q "%USERPROFILE%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates"

del /Q "%USERPROFILE%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\active-update.xml"

del /Q "%USERPROFILE%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates.xml"