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Reset Firefox preferences to troubleshoot and fix problems

Resetting preferences (zoom, tabs, privacy, network, encryption, updates, where to save file downloads, etc.) is one of many procedures that can be helpful in troubleshooting Firefox problems. We'll explain two ways to do this.

Solution 1: Refresh Firefox

Note: When using the refresh feature, your bookmarks, browsing history, open tabs, windows, passwords, cookies and web form auto-fill information will be saved. However, your extensions and themes will be removed and your preferences will be reset. Learn more.

  1. Click the menu button New Fx Menu and then click help Help-29 .
  2. From the Help menu choose Troubleshooting Information.
    If you're unable to access the Help menu, type about:support in your address bar to bring up the Troubleshooting Information page.
  3. Click the Refresh Firefox button in the upper-right corner of the Troubleshooting Information page.
    Refresh 35 Win Refresh 35 Mac Refresh 35 Lin
  4. To continue, click Refresh Firefox in the confirmation window that opens.
  5. Firefox will close to refresh itself. When finished, a window will list your imported information. Click Finish and Firefox will open.
Note: There's also a Refresh Firefox button in the Firefox Safe Mode window, if you can't start Firefox normally. If you are unable to find the Refresh Firefox button on your version of Firefox, you can also do a manual refresh by creating a new profile. See instructions on how to create a new profile.

Solution 2: Delete Firefox preference files

  1. Click the menu button New Fx Menu , click help Help-29 and select Troubleshooting Information. The Troubleshooting Information tab will open.

  2. Under the Application Basics section, click on Show FolderOpen FolderShow in FinderOpen Directory. A window with your profile filesfolder will open.
  3. Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.
  4. Click the menu button New Fx Menu and then click ExitQuit Close 29 .
  5. Locate and delete the file prefs.js (or rename it, for example, to prefs.jsOLD, to keep the old file as a backup). If you find more than one, a prefs.js.moztmp file or a user.js file, delete (or rename) these as well.
  6. You can close the profile folder and open Firefox now.
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Comments

I reworded Intro and added a link to the How to fix preferences that won't save troubleshooting article.

Starting in Firefox 15, the Firefox Safe Mode window will no longer include the option, Reset all user preferences to Firefox defaults. See Bug 732303 - Redesign safe mode dialog with the profile reset option and comment 26

The redesign will remove all of the Safe Mode checkboxes and simply offer the options to continue in Safe Mode or Reset Firefox. Instead of using Safe Mode to reset preferences, users can delete the file prefs.js from the Firefox profile folder (and, according to the bug comment 26, the "preferences" directory if it exists?)

Related discussion:

Michael Verdi updated this article on July 31, 2012 to replace the Safe Mode instructions for resetting all user preferences to Firefox defaults, with Reset Firefox instructions from Refresh Firefox - reset add-ons and settings, back to Firefox 13. I think that consideration should have been given to continuing the Safe Mode instructions for Firefox 14, since they still work. I also think that consideration should be given to including a less destructive method for Firefox 15 users who just want to reset user_prefs which would be opening the Firefox profile folder from the Firefox Help -> Troubleshooting Information page and then closing Firefox and deleting the prefs.js file. I mentioned this today in another discussion, https://support.mozilla.org/forums/contributors/708557#post-48158 ...which I'll copy below:

AliceWyman said

Tylerdowner said
Just as a side note, we already have the Reset Firefox Feature (Refresh Firefox - reset add-ons and settings), which will fix the issue of the about:home being taken over if the user is that far infected.

Yes but that may be overkill, if all you need to do is reset user_prefs, which is described in MozillaZine's Resetting preferences article.

By the way, I see that the SUMO resetting preferences article no longer explains how to reset just user preferences. It now tells you to use the Reset Firefox feature. The old instructions are now only given for Firefox ESR, even though you can still use Safe Mode in Firefox 14 to reset all user preferences. (I don't think the article ever explained how to delete prefs.js as an alternate method for resetting all user preferences, like MozillaZine's article does.)

Jan started working on this the other day and I think I incorporated what Alice suggested here.

Thanks, Michael.

I noticed the change Jan. made to this article and was going to comment here about it until I saw that you had restored the previous version :-(

I'm glad you incorporated both solutions.

I know current policy is to recommend Firefox Reset wherever possible, but in this article we have documented the deleting prefs.js solution in order to deal with sart-up crashes etc.

Should we consider mentioning

  1. It is less effective than a full Firefox Reset.
  2. That renaming rather than deleting the file is a better and easily reversible solution.

John99 said

I know current policy is to recommend Firefox Reset wherever possible, but in this article we have documented the deleting prefs.js solution in order to deal with sart-up crashes etc. Should we consider mentioning
  1. It is less effective than a full Firefox Reset.
  2. That renaming rather than deleting the file is a better and easily reversible solution.

Deleting the prefs.js file accomplishes the original purpose of this article (resetting preferences to Firefox defaults) which is the option that Firefox Safe Mode used to include. It's less destructive than a Firefox Reset and if you follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article, it's one of the cases where the problem still exists in Firefox Safe Mode.

I made a revision to add that you can also rename the prefs.js file instead of deleting it. The rest of the article seems OK.

AliceWyman said

I made a revision to add that you can also rename the prefs.js file instead of deleting it. The rest of the article seems OK.

Excellent choice, revision accepted, a backup is always useful in such cases.

info_847048

Monday, June 27, 2016


How do I fix Firefox a image upload problem? Recently, I have not been able to use the upload feature on Firefox to upload images. I've had to switch to Chrome to perform this feat. As recent as today, I was not able to upload an image to my Linkedin profile using Firefox but the same sized image uploaded fine using Chrome?

Hello ClassicShoppes,

sorry but this forum is not the place for getting help. In this area contributors discuss for that specific article("Reset Firefox preferences to troubleshoot and fix problems"). :-)

please ask the question in the support forum, use the next link for that, and definitely someone will help you :-)

https://support.mozilla.org/en-US/questions/new

thank you :-)