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Firefox error resolved: One or more files could not be updated

I have automatic updates enabled in Firefox. For my day-to-day work, I run as a non-administrator user in Windows XP. I need to log in as an administrator whenever I want to install new software - including updates for Firefox.

The problem is that Firefox is not content to just update all necessary files when you are logged in as the administrator. When you return to your non-admin account and launch Firefox, you may be greeted with the following message:

"One or more files could not be updated. Please make sure all other applications are closed and that you have permission to modify files, and then restart Firefox to try again."

You can click through the message, and Firefox will launch anyway. Okay, I guess the updates weren't that important and I can ignore the message. However, the next time I launch Firefox, and am again prompted and again click through it. It seems I am doomed to launching Firefox with two clicks for all eternity.

Of course I searched the internet for the error message, but nothing very fruitful came of it. Apparently the error has a number of different causes. I did find some others reporting the problem when run as a non-administrator, but the solution was always "just run as administrator" or "elevate your rights".

I finally solved the problem without changing any rights for my user account, and am now posting it here in hopes that others will find it useful.

UPDATE: Based on suggestions in the comments, I've started using a much simpler method. If you have an administrator password, you can run the following command in a Command Prompt:

runas /user:Administrator /noprofile /env "C:\Program Files\Mozilla Firefox\firefox.exe"

The rest of this article is unnecessary if you want to follow this "delete the updates folder" approach.

Note: you must be able to log in as an administrator on the computer, but your primary user account does not have to be an administrator.

Pre-requisite: As an administrator, download and install Process Monitor from Sysinternals/Microsoft.

  1. Close all running instances of Firefox.
  2. Open an Administrator command prompt by right-clicking on a Command Prompt icon, choose Run As... and enter the credentials of a user with administrator rights.
  3. Launch Process Monitor from the administrator command prompt by typing the full path to the executable (wherever you installed it). For example: c:\apps\procmon.exe (tab completion can be very helpful for this step).
  4. Within Process Monitor, turn off "Show Registry Activity" and "Show File System Activity" from the toolbar. Only "Show Process and Thread Activity should be enabled". This step is not absolutely necessary, but it will eliminate a lot of extra noise.
  5. Start Firefox, and click through the "Software Update Failed" dialog until the browser opens.
  6. Switch back to Process Monitor and press CTRL-E or the click the toolbar button to stop capturing events. Close any Firefox windows that might be open.
  7. Scroll through the list of processes and double-click on the first instance of "updater.exe" (it should have the value "Process Start" in the Operation column). Switch to the Process tab of the Event Properties window that opens.
  8. Select the entire contents of the "Command Line:" textbox and copy it (CTRL-C or right-click, Copy). It should look something like this (all one line): "C:\Documents and Settings\Josh\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates\0\updater.exe" "C:\Documents and Settings\Josh\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates\0" "3824" "C:\Program Files\Mozilla Firefox" "C:\Program Files\Mozilla Firefox\firefox.exe"
  9. Switch back to the administrator command prompt and right-click, Paste to paste the command-line. Press Enter.
  10. You should see a dialog indicating that Firefox is updating. Close the browser that opens since it is still running as the administrator.
  11. Now open Firefox normally. It should start up without the annoying error message.

I'm not sure if the command-line from step 8 is always the same (the "3824" is the only part I can imagine would vary). If it is always the same, you can save a lot of steps on subsequent updates by just creating a batch file with that command and running it as administrator. If anyone has any insight to the parameters of this command, let me know.


1) launch Firefox as administrator and update it;
2) (logged in as standard user, not administrator) delete this folder:
C:\Documents and Settings\%username%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox
Io - June 19, 2007 08:02am
I'll have to give that a try next time. The update will still be applied to the non-admin user? What is it that we are deleting in that folder?
Joshua Flanagan - June 19, 2007 11:31am
You wrote:
> I'm not sure if the command-line from step 8 is always the same (the "3824"
> is the only part I can imagine would vary).

Thanks for the solution; it worked perfectly. On the system I just had to fix, the number happened to be "3324". If it happens again on the same computer (and under the same user name) I wonder if the number will change.
Michael - June 19, 2007 04:28pm
Thanks for this page... that warning was getting quite old.

The "3824" was the Parent process ID I think, so it will change each time, but doesn't seem to be important as that process is gone when you launch this from command line per your instructions... I'd imagine you could just put "9999" or whatever into a script and I might work (haven't tried it).

The only problem I had with your fix came at step 9. When I tried to run from admin prompt I kept getting 'access denied' messages. Eventually I just tried it from the regular, non-admin prompt and it worked fine. I did tweak a few things in between though and can't say if they had any effect (changed some permissions, etc.).

Anyway, thanks again for this post.
Joseph - June 28, 2007 09:39pm
Oops, I lied... it didn't get fixed. But I tried Io's fix noted above and that worked perfectly. I am pretty sure about that process ID thing though...
Joseph - June 28, 2007 09:46pm
Didn't try your fix but Io was right on the money for me. The folder contained the file update-auto.xml or something like that. Pretty sure it was the culprit.

Brett - June 29, 2007 08:23pm
So does following Io's suggestion make the error go away because the update can complete successfully OR does the error go away because once that file is gone, Firefox stops trying to update your software? In other words, when you delete those files, do you still get the upgrade?
Joshua Flanagan - June 30, 2007 06:52am
Thanks both to Joshua and Io. Given the open source origins of Firefox, it is indeed perplexing that the program does not envision run/as installations. I tried Io's deletion tweak and that seems to work.
william - July 05, 2007 09:49am
Io's solution worked for me. We're running Firefox on a Windows Terminal Server and several folks were getting this error. What happened is that the users were getting the above folder filled with the updates and then even if the Administrator logged on to apply the updates, the user's Updates folder still contained items.

I tried removing FF and reinstalling (but the users' local settings folder wasn't cleaned out so kept trying to launch updates unsuccessfully). I tried giving all users Full Control NTFS permission on the Firefox folder but again, they didn't have the permission to even run the updates in the first place. This worked but the pain in the butt is having to have all users rename their folder manually. Well, it's that or doing it for them which would have taken an hour which we didn't have.

I've been looking all over for this solution but it finally works. Finally!
David Dawson - July 10, 2007 04:17pm
Thanks for this.
It annoyed me for a long time, but now it works perfectly. :)
Bart - July 13, 2007 01:29am
"One or more files could not be updated. Please make sure all other applications are closed and that you have permission to modify files, and then restart Firefox to try again."

I solved this one, as a limited user clear the contents of \0 folder. also if you have the \profile folder remove this folder, that's it. I didn't have the above error message pop up again since. It worked mine.
tiks - July 17, 2007 04:02pm
Io said:

1) launch Firefox as administrator and update it;
2) (logged in as standard user, not administrator) delete this folder:
C:\Documents and Settings\%username%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox


It works perfectly. Thank you!.
OnFire - July 19, 2007 08:34am
The problem is if you delete your entire local settings for Firefox as Io suggests, you also nuke whatever extensions you had installed, which is not quite desirable.
Tamori - July 19, 2007 05:00pm
I just deleted the Updates Folder in Local Settings > Application Data > Mozilla.

That worked perfectly.
M - July 19, 2007 05:30pm
Your solution may well work, however it is rather convoluted for you average mum & dad level user.

I actually solved the problem by logging on as Admin user and checking the access permissions on the "C:\Program Files\Mozilla Firefox" folder. The "Users" group was only allowed
1. Read & Execute
2. List Folder Contents
3. Read
access permissions. I added "Modify" which automatically included "Write" permission.

Logged back on as a normal User level user.
Span Firefox up again and the update went through without a problem, also including all the addin checking that is part of a proper update.

Can I suggest that you try this first before going through all the above hoops.

On a cautionary note, I am fairly sure I did this as part of the last update so there may be something that is part of the update process which when run on your Admin account re-sets the permissions on Mozilla Firefox folder back to the state that causes this problem to normal User level users when they come to run the update. So you may need to make this a regular part of your Firefox update process. So if this works for you "MAKE NOTES FOR THE NEXT TIME".
RiggsFolly - July 23, 2007 05:49am
RiggsFolly - I was specifically trying to solve the problem WITHOUT changing permissions for my limited user account. Well behaved applications should not require regular users elevating their permissions.
I agree my solution is not really viable for non-technical users. Your solution is definitely the most straight forward if you are not concerned about the security implications. It was good to point out, so that readers know they have other options. Thanks!
Joshua Flanagan - July 23, 2007 08:05am
This is clearly a bug in the Mozilla update procedure. I agree with Josh and William Douglas - you shouldn't have to change permissions on the application folder, and you should be able to use "Run as" to update Firefox.

Even as an administrator, however, Josh's first solution is too complicated for me. \ I don't understand what all that accomplishes. I opted for the simpler "delete these user files" approach.
Catemaco - July 24, 2007 07:34am
I also prefer the "delete these user files" approach. I'd like to better understand what the files are - why is it safe to delete them? Am I losing something by deleting them?

My solution is way too complicated, but it was the only thing I could come up with to make that annoying dialog go away. My post also provides a place for everyone else having the problem to find potential solutions.
Joshua Flanagan - July 24, 2007 08:43am
We all want to be certain users without administrator permissions are running up-to-date browsers. If deleting the folder means deleting the update, that could be a security risk.

Can anyone explain what's in that folder? I'd really appreciate it, especially if deleting it means reinstalling all the extensions every time Firefox needs updating.
Beth - August 01, 2007 09:28am
Tiks wrote:
"I solved this one, as a limited user clear the contents of \0 folder. also if you have the \profile folder remove this folder, that's it. I didn't have the above error message pop up again since. It worked mine."

As an experiment, I just renamed the \Documents and Settings\%username%\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates\0 folder. (I think that's the one you're refering to, right Tiks?) I didn't have to use administrative login for anything, and I didn't bother with the \Application Data\Mozilla\Firefox\profile folder. As soon as I restarted firefox, the installation ran, and a new \0 folder was added, so I guess that sort of answers my previous question. As for extensions, I didn't have any, so I don't know if they would have been nuked or not.
Beth - August 01, 2007 09:40am
That's right Beth.
Tiks - August 07, 2007 09:16am
I create a script and run it each time I install the new firefox
copy-past the script below in a file named like "delete_firefox_folder.vbs"

'Check on all the user profiles where the folder of the profile are less then 5 caracters and then,
'Delete the folder Mozilla if existe in the path "C:\Documents and Settings\<initials>\Local Settings\Application Data\"
Set FSO = CreateObject("Scripting.FileSystemObject")
ShowSubfolders FSO.GetFolder("C:\Documents and Settings")
'Enumerating all the folder include the subfolders
Sub ShowSubfolders(Folder)
For Each Subfolder In folder.subfolders
folder_name = right(Subfolder.path,len(Subfolder.path)-InStrRev(Subfolder.path,"\"))
If len(folder_name) < 5 Then
If (FSO.FolderExists(Subfolder.path+"\Local Settings\Application Data\Mozilla")) Then
FSO.DeleteFolder(Subfolder.path+"\Local Settings\Application Data\Mozilla"), True
End If
End If
End Sub
Gabriel - August 09, 2007 07:40am
I tried the solution proposed by Beth (her message from Aug 1st) and it worked perfectly. Thanks!
Dominique - August 19, 2007 05:49am
A more simple solution...
In the command line of the limited user, paste and execute the following line:

runas /user:Administrator /noprofile /env "C:\Program Files\Mozilla Firefox\firefox.exe"

The "/noprofile" and "/env" flags will launch Firefox with administrator permissions but without loading the Administrator's profile and will continue to use the current environment. Firefox will then update as necessary and open a browser window. Firefox can then be restarted with the limited user's permissions and will cease to complain.
Justin - September 20, 2007 08:46pm
Great info, thanx all.
Justins last trick seems the most reasonable to me, and it works wonders. Just remember you have to have the Administrator password at hand (of course). Thanks.
Fabian - September 26, 2007 10:41am
Geez, I continue to have this problem with new updates! When is the dev team gonna fix it?
Dave C. - December 12, 2007 09:10pm
Eliminated years worth of pain
Koti - January 24, 2008 02:59pm
If UserIsAdmin()

Cmon Mozilla team, how hard can this be?
Dave S. - April 18, 2008 12:36pm
THANK YOU. I was getting very frustrated not only with this message but also with the complete lack of useful information on the Mozilla forums.
Jay Schlackman - April 21, 2008 01:33pm
Try also this solution:
Giuseppe M. - June 17, 2008 01:33am
Amazing that this is still a problem. Get with it Mozilla!
Dave C. - December 20, 2008 03:28pm
Thanks for saving my sanity. That error message was getting on my last nerve, especially since I have been looking for a fix for months to no avail. I found many people with the same problem but not able to find a fix as well. Here's hoping they find your post too. I am glad I did not give up my search, and I can not thank you enough for your post that fixed the problem. Keep up the good work.

Melissa Battersby - January 11, 2009 02:18pm
Thanks so much. Perfect
Greg - October 09, 2009 07:11am