Tap here to go to the mobile version of the site.
Your Firefox is out of date and may contain a security risk! Upgrade Firefox

Support Forum

Updated Firefox won't save my preferences; reverts to original settings.


A few days ago, Firefox updated itself to the 18.0.1 version. Now, each time Firefox updates itself, I tend to lose some of my preferences, those being: opening new tabs as a blank page, tabs being on the bottom, and showing my windows and tabs from last time. Usually, though, once I go and change these things back to the way I like them, they stay like that and I have no further problems.

However, this time Firefox won't save my preferences. The tabs go back to being on top, the tabs I last closed aren't there, and these tool bars I don't want keep appearing. Instead, three tabs are always there upon opening Firefox: Welcome to Firefox, Mozilla Firefox Start Page, and Yahoo! Toolbar. Also, when opening a new tab, the page says, "page does not exist" or something, and the URL is not even comprehensible, just random letters like someone bashed their head into the keyboard, something like: "jkfui87$^&%$$09."

I've tried resetting Firefox like it says in the "How to fix preferences that won't save" page, but it didn't help. As for deleting certain files from the profile folder, before I resetted Firefox, I only had "user" and "prefs" and "Invalidprefs" which weren't exactly what that self-helping page asked for so I didn't delete them. After I resetted Firefox I lost the "user" file, but I still have the other two. Should I try deleting them even if they're not exactly like the page describes? They are missing the ".js" part so I haven't felt comfortable messing with them.

Please give me some advice. I'm tired of having to go change my settings in "about:config" each time I open Firefox. But I really don't want to try anything that would delete my bookmarks or history, as I'm very dependent of them.

Additional System Details

Installed Plug-ins

  • Next Generation Java Plug-in 1.6.0_39 for Mozilla browsers
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Shockwave Flash 11.5 r502
  • RealPlayer(tm) LiveConnect-Enabled Plug-In
  • RealPlayer Download Plugin
  • Adobe PDF Plug-In For Firefox and Netscape 11.0.01
  • SiteAdvisor
  • RealNetworks(tm) RealDownloader Chrome Background Extension Plug-In
  • RealNetworks(tm) RealDownloader PepperFlashVideoShim Plug-In
  • RealNetworks(tm) RealDownloader HTML5VideoShim Plug-In
  • RealDownloader Plugin
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • Adobe Shockwave for Director Netscape plug-in, version
  • Google Update
  • RealNetworks(tm) RealPlayer Chrome Background Extension Plug-In
  • RealPlayer(tm) HTML5VideoShim Plug-In
  • 4.1.10329.0
  • Adobe Shockwave for Director Netscape plug-in, version
  • DivX VOD Helper Plug-in
  • DivX Web Player version
  • Reader Library Helper Plugin
  • Delivery Network Acceleration by BitTorrentâ„¢
  • Windows Presentation Foundation (WPF) plug-in for Mozilla browsers
  • DRM Netscape Network Object
  • Npdsplay dll
  • DRM Store Netscape Plugin
  • Yahoo! activeX Plug-in Bridge
  • Rhapsody Player Engine Plugin


  • User Agent: Mozilla/5.0 (Windows NT 5.1; rv:18.0) Gecko/20100101 Firefox/18.0

More Information

  • Top 10 Contributor
  • Moderator
10756 solutions 96800 answers

Helpful Reply

Windows XP hide some file extensions and .js is one of them, so the user file is likely user.js.

What is the content of the user.js file if you open it in Notepad?

The user.js file isn't there by default, so other software must have created it if you didn't do that.

The user.js file is read every time Firefox is started and prefs set in user.js will override settings from the previous session saved in prefs.js.
So prefs that are set via user.js can't be changed permanently and changes made in Firefox only last for the current session.

Question owner

I went to that link you provided and tried the "Corrupt or damaged prefs.js file" section of it, but still, my preferences aren't being saved. Since I resetted Firefox, I don't have a "user" file anymore. I'm really not sure what else to try.

  • Top 10 Contributor
  • Moderator
10756 solutions 96800 answers

Did you delete both (JScript) prefs files in the current Firefox Profile Folder?

Some security software has virtualization or sandbox features that may cause problems by protecting and restoring files in the Firefox profile folder.

Question owner

Hi, sorry it's taken me so long to reply. I've been noticing something strange and wanted to monitor it for a few days.

So, sometimes I'll open firefox and my settings will all be saved. More often I'll open firefox at my preferences have again be resetted, my tabs from last time aren't there again and I have these tabs welcoming me to firefox. I have no clue what's going on. I've already deleted all the prefs files.

LotusSteve 0 solutions 2 answers

My partner had this problem on a newly purchased laptop, it was down to a programme (BrowserProtect) that was an original instalation. Removed the programme and all was well.

pauldb13 0 solutions 5 answers

Followed all directions and Firefox 21.0 still won't save preferences. Also back button still doesn't work. Get these problems both in regular and safe-made.

Also just tried to refresh this page and refresh button doesn't work. None of the navigation buttons work. Uninstalled and did a clean install and still get these problems.

Wondering if Firefox is even worth it anymore.

Modified by pauldb13

  • Top 10 Contributor
  • Moderator
10756 solutions 96800 answers

Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

Download a fresh Firefox copy and save the file to the desktop.

Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.

  • Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you will lose all personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

  • (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
  • (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.

If you keep having problems then also create a new profile.

pauldb13 0 solutions 5 answers

Did that and still have the problem. Even went through the safe-mode restart and has the problem even in safe-mode. What next?

Modified by pauldb13

  • Top 10 Contributor
  • Moderator
10756 solutions 96800 answers

You can rename or delete the prefs.js file and possible numbered prefs-##.js files and a possible user.js file to reset all prefs to the default value.

Create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

If the new profile works then you can transfer some files from an existing profile to the new profile, but be careful not to copy corrupted files.

pauldb13 0 solutions 5 answers

Helpful Reply

Obviously no one here actually READS these things, I tried all of that even did a clean install, even uninstalled all user data and THE PROBLEM IS STILL THERE!

Your help is completely useless, All you people do is copy and paste the same thing over and over. If it didn't work the first 20 times it's still not going to work no matter how many times you copy and paste the same fucking link.

You have lost a die hard fan of Firefox, I am switching to another browser.

Unfortunately I tried older versions of Firefox and had to go all the way back to Firefox 4 and now the problem is fixed.

Modified by pauldb13

  • Top 10 Contributor
  • Moderator
10756 solutions 96800 answers

Updating Firefox shouldn't effect preference settings that you can inspect on the about:config page.

If that is the case then there is usually security software involved that is either restoring files or is preventing Firefox from updating files in the profile folder otherwise.
A lot of security software now have some virtualization or sandbox feature that cause such issues.
So you will have to check there.

Boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.

pauldb13 0 solutions 5 answers

Did that and the problem still persists.

Just tried turning off my anti-virus and problem still persists.

Modified by pauldb13

Mladenov 0 solutions 1 answers

There is the soltion. You don't need to reinstall Firefox. There is a file, which is responsible for this option. It is not written by Firefox, but it comes from Windows. So You can solve this problem following this: go to

C:\Users\..your user name ..\AppData\Roaming\Mozilla\Firefox\Profiles\59nd6xuh.default

and find the file called user. Open it with Notepad (or other text editor) and find the row:

user_pref("browser.startup.page", 1);.

That "1" means "Show my home page" (in Firefox browser: Tools->Options) It could be "2", and means "Show a blank page", or 3 - "Show my windows and tabs from last time". You can just delete the row from the "user" file and so the problem shell be solved. You can also add the entries "2" and "3". The row must look like that:

user_pref("browser.startup.page", 1,2 ,3);


user_pref("browser.startup.page", Show my windows and tabs from last time);

Now you can change your option in Firefox: Tools->Options->When Firefox starts:->choose the option you want

I hope it helps you. Good luck!

Modified by Mladenov

  • Top 10 Contributor
  • Moderator
10756 solutions 96800 answers

This user.js file is only there if you or other software has created it, so it shouldn't be there.
You may want to check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read on every start of Firefox and preferences set via this file will be set to the value specified in user.js on every start of Firefox and can only be changed temporarily for the current session.