This article in our support base may help: https://support.mozilla.org/en-US/kb/stop-firefox-opening-multiple-tabs-when-it-starts?esab=a&s=tabs+opening+when+firefox+starts&r=0&as=s

Thanks for the link Roger but the article is dealing with a different issue and doesn't solve my problem.

You can check if you have a user.js file in the Firefox profile folder that sets the browser.sessionstore.resume_session_once pref to true.

• http://kb.mozillazine.org/browser.sessionstore.resume_session_once

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

See also:

• http://kb.mozillazine.org/Preferences_not_saved

In the past 24 hours Firefox has developed the same problem which has not been resolved by update to Firefox 32. I have tried all of the above suggestions, as well as disabling all add-ons, with absolutely no effect. Firefox is set to open in my home page, browsersessionstore.resume_session_once is set to false and there is no user.js file.

Is there any way to fix this problem?

You can check for problems with the sessionstore.js and sessionstore.bak files in the Firefox profile folder that store session data.

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Multiple_profile_files_created

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost and you will have to recreate them (make a note or bookmark them if possible).

Hi, cor-el,

I have a sessionstore.js and a sessionstore.bak file. Can I delete both?

If you aren't interested in tabs that are saved in those files then you can delete them. Firefox will create new files. When Firefox is started then Firefox renames the sessionstore.js file to sessionstore.bak to make it possible to restore the previous session (History > Restore Previous Session).

Note that Windows hides some file extensions by default. Among them are .html and .ini and .js and .txt, so you may only see user file name without .js file extension. You can see the real file type (file extension) in the properties of the file via the right-click context menu in Windows Explorer.

• http://kb.mozillazine.org/Show_hidden_files_and_folders

I have a user.js file but no way of reading its contents. Can I safely delete it?

Yes, you can delete the user.js file. You can right-click the file and open it in a text editor (Notepad) for inspection, so do not double-click the file as that will give an error (Windows sees it as a JScript file).

The user.js file is only present if you or other software has created this file and normally it wouldn't be there. You can check its content with a plain text editor (right-click: Open with) if you didn't create this file yourself.

The user.js file is read each time Firefox is started and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

Problem solved by deleting user.js. Thanks a million!

hello. i get to the profile folder, and even see the user.js file, however, i understand that i am supposed to open this folder? it doesn't seem to open or there is nothing there when you open it. i am having the same problem, a bunch of tabs/pages appear (seem to be the same ones) when i open firefox up to start a new browsing session. all i want is the homepage. do you have further detailed instructions? am i just missing something? thanks for any help you can provide.

You can delete the user.js file or check its content in a text editor (Notepad) via the right-click context menu (Open with) to see which prefs are affected. Do not double-click this file as this causes a JScript error.