You may have corrupt sessionstore file(s).

Type about:support in the address bar and press enter.

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

Locate the sessionstore file(s). Then rename or delete them. Restart Firefox.

When you say delete all sessionstore files. I only see one - sessionstore.js I deleted it and restarted Firefox. What other files should I have deleted? sessionCheckpoints.json? sessionstore-backup folder and all files? If I need to delete more, please let me know.

Now keep in mind everytime I've had this problem happen, I deleted sessionstore.js and renamed previous.js to sessionstore.js So in effect I've already deleted that file several times without any success.

What I understand is if I delete sessionstore.js Firefox takes recovery.js and renames that sessionstore.js Maybe you know something more and this will work, please explain how this is different from what I've already done.

I really appreciate your help,

Rename sessionstore anything.

FredMcD said

Rename sessionstore anything.

Right, I always instead of deleting rename it, just in case I'll need it later. It appears I've already done this several times without it fixing this problem. Do you have any more suggestions?

Thanks,

If you use "Clear history when Firefox closes" then try to disable this feature.

• Tools > Options > Privacy > Firefox will: "Use custom settings for history": [X] "Clear history when Firefox closes" > Settings
• https://support.mozilla.org/kb/remove-recent-browsing-search-and-download-history

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
• Mac: Firefox > Quit Firefox
• Linux: File > Quit

I've never used the "Clear history when Firefox closes". I've always had lots of tabs every single time I've closed Firefox. I also have about 30 tab groups. I've been using Firefox for years.

Upgrading to Win 10 about 2 weeks ago is when this bug started for me. When it malfunctions and I open Firefox I see tons of tabs, but every single one is blank and says "New Tab" and when I open tab groups, no tab groups are there at all.

I've always hit the upper right x to exit, except sometimes I go to the task bar and right click and choose exit. I'll try to remember to so Windows: File > Exit and see if that works. This bug happens about 5-10% of the time, so most of the time it's fine.