You may have corrupt sessionstore file(s). Delete all sessionstore* files and the sessionstore-backups folder.

Type about:support< enter > in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file. Then rename or delete it. Restart Firefox.

FredMcD zei

You may have corrupt sessionstore file(s). Delete all sessionstore* files and the sessionstore-backups folder. Type about:support< enter > in the address bar. Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox. Locate the above file. Then rename or delete it. Restart Firefox.

Hai FredMcD, After deleting the files / folder I restart FF. Nothing changes unfortunitly. I have gathered some more information: When clicking the Home icon (in the right top-corner I see my defind startpages. After clicking my startpages were twice on the screen but stil once in the configuration. When repeating this steps I get a lot of times my startpages on the screen by starting FF. I sent you some screencaptures as an example.

I am looking forward to your answer.

Could your add-ons be the problem?

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Hi FredMcD,

The problem is still there. I did it twice times but no result.

Hi   Kees   !
Would you try this :

Type in the address bar about:config (promise to be careful, if asked) Type and look for the preference : browser.startup.homepage and make sure that it's value matches your desired home page

Hi Happy112,

The value in browser.startup.homepage matches my desired home-page.

One of the config-startup-options is "showing the tabs of the last session". What happens by startup FF, looks like the same as the description of this option.

Kees1712 said

One of the config-startup-options is "showing the tabs of the last session". What happens by startup FF, looks like the same as the description of this option.

And that is exactly what you don't want, right   ? Is it's value set to   false   ?

That's right. What is the name of that config. parameter?

And: When I place the mouse above the Home button in the top-right corner then I see the my start-pages as a pop-up. When I click on that button FF ads my start-pages at the end of the existing pages on the screen, so I see my startpages doubled. Clicking again, than I see my startpages three times and so on.

I seems that FF forget to "clear" the existing pages before starting my startpages.

Kees1712 said

Hi FredMcD, The problem is still there. I did it twice - but no result.

Don't know if you have any add-ons,   but if you do :
After they were disabled,   did you then enable them one by one   ?

Even when I start in save mode the problem is there. As I said earlier, clicking on the Home button adds new tabs tot the existing tabs in stead of showing only my startup pages. Is it an idea to delete all the directories of FF and install again?

It is possible that Firefox isn't closing properly if you get tabs from the previous session.

Use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar.

• "3-bar" menu button -> Exit (Power button)
• Windows: File -> Exit (Bestand > Afsluiten)
• Mac: Firefox -> Quit Firefox
• Linux: File -> Quit

Also check in the Windows Task Manager if there are any Firefox processes left after you close Firefox.

I wouldn't go do anything drastic right now.
Maybe you'd like to give this add-on a try   :
https://addons.mozilla.org/en-US/firefox/addon/new-tab-homepage/

Also I'd like you to take a look at the article :
How to fix preferences that won't save

Hi all of you,

My problem is fixed! The article "How to fix preferences that won't save" describes a solution based on the content of the file "user.js" in my profile. The bottom line contains: user_pref ("browser.sessionstore.resume_session_once", thru);

I 've changed the value from thru --> false and that fixes my problem.

I 've no idea why or how this value was set to the wrong value but anyway I 'm happy that it is fixed. Thank you for your help and suggestions!!

Friendly regards from Kees1712

That was very good work. Well done.

You should change the value of the pref to false in user.js, but you need to remove this line completely or delete the entire user.js file if you didn't create it yourself.

The legit use of this pref is to make it possible to restart Firefox to apply an update or to finish the installation of an add-on. If you would set this pref to false via user.js then you will lose the tabs from your current session in this case.