Are you currently using a version from the repositories of your Linux distribution? Try the Firefox version from the official Mozilla server: https://www.mozilla.org/en-US/firefox/all/

Are you currently using a version from the repositories of your Linux distribution? Try the Firefox version from the official Mozilla server: https://www.mozilla.org/en-US/firefox/all/

Yeah, download to a folder and run it from there. I stopped running the distro version as my daily driver many months ago because I was losing tabs.

And . . . .

I am using the latest Ubuntu repository version and would prefer to continue to do so if possible.

I found that all was OK if I created a new blank profile. I suspect that if I download a new version I will have the same problem using my old profile.

I am still trying to work out how to import my passwords into the new profile.

When you are ready, we can start moving parts of your old data and Copy it to the new profile.

First; open your file browser to the New profile;

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.

Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder

Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory.

Second, open another file browser to the Old profile. You should see it on the directory "tree" in the first file browser. Right-click on that folder and select Open In New Window.

Warning ! ! Only Copy the files you are told. We will avoid anything that might cause problems. Here is the list of files;

cookies: cookies.sqlite Do not bother. Cookies will be created when you return to the website. However, you will have to log in everywhere. And you may lose any settings that websites store on your computer.

extensions(add-ons, themes): it would be better to download them fresh. If you need to remember what add-ons you had, open the extensions sub-folder and look at the .xpi files

logins.json and key3.db [v58+]key4.db : These are the password files. Copy Both !

persdict.dat : custom dictionary - words you added to the dictionary

mimeTypes.rdf [v55+]handlers.json : What to do with what type of file.

places.sqlite : History and Bookmarks.

prefs.js : Your settings. Note: If you were having problems, this could be contaminated.

cert8.db [v58+]cert9.db and possibly cert_override.txt : Stores all your security certificate settings and any SSL certificates you have imported into Firefox. If removed, the cert8.db, cert9.db file will be replaced.

search.json.mozlz4 : file stores the user-installed search engines that are available in the Firefox v47+

search.sqlite file and searchplugins folder store the search engines that are available in the Firefox Search bar before Firefox v47

Copy these files from the old to the new. You may get a message that the files already exist. Choose to over-write for each file.

Thank you for these detailed instructions! No time now but I will get into it this evening.

Why not use Sync? https://support.mozilla.org/en-US/kb/sync-logins-firefox-desktop

You can run a 2nd Firefox from a folder. It's also a good backup of your browser data having more than 1 browser.

@jonzn4SUSE

Thanks for the suggestion. I looked at that. Don't I need access to the menu to use Sync?

Problem solved!

I tried the changes incrementally, finding that the old prefs.js file was indeed the problem. So I ended up using my original profile with the new prefs.js file replacing the old one. I just had to play with my settings to get things back to how they were

Thank you FredMcD for your help with this.

Glad to help. Safe Surfing.