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

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New User

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.

14 REPLIES
Site Moderator

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

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.

New User

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

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.

Site Moderator

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

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.

New User

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

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.

New User

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

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.

New User

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

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.

Site Moderator

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

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.


New User

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

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

Site Moderator

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

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.