Note: all versions of Firefox will force upload and does not matter the settings : Going back : unfortunately 56.0.2 and below is no longer safe to use for every day use do to secuity issues, but 52.5.0 ESR is. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ Note : Legacy Extensions will be deleted or removed in any version update after May 2018.

You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Please let us know if this solved your issue or if need further assistance.

For lost tabs, Restore Previous Session is the first thing to try. If it's grayed out, either the session was already restored or the file was not available/corrupted.

Either way, the next thing to check is "Recently Closed Windows" and "Recently Closed Tabs". These can be found either:

• Using the "Library" button on the toolbar, History submenu. (This button looks like some books on a shelf.)

• Using the History menu on the classic menu bar. Tap the Alt key or the F10 function key to activate the menu bar temporarily if you don't normally display it.

I also encourage you to back up all your current session history files. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter/Return

In the first table on the page, click the "Open Folder" button (Mac: "Show in Finder" button). This will open a new window listing your profile folder contents.

Scroll down and double-click into the sessionstore-backups folder. Save all files here to a safe location, such as your Desktop or Documents folder. If not too much time has passed, we may be able to use them to recover your lost tabs.

The kinds of files you may find among your sessionstore files are:

• recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.bak: a backup copy of recovery.js
• previous.jsonlz4: the windows and tabs in your last Firefox session
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update
• various files with a .js file extension from Firefox 55 or earlier

To preview the contents of a file, you can drag and drop it onto this page, then click Scrounge URLs: https://www.jeffersonscher.com/res/scrounger.html

That tool is on my site, so please let me know if it doesn't work for you.

Any files look promising?

Most sincerely, jscher2000, THANK you for the detailed response. The problem may be primarily mine because I DELETED the FF app and then let Hazel trash related files.

Anyway, Quantum, with its SQUARE tabs is simply uglier than either Chrome or Safari.

And, as I pointed out in regard to the blocking of the Google domain, that is something I can't live with at all, since most of what I do has to do WITH Google!

I really can't imagine what Mozilla has done here. It is entirely beyond my ken.

AS a Systems person for 38 years, I can't IMAGINE treating users this way or foisting ANY upgrade so disastrous upon them. Had I ever done that my head would have rolled!

Pkshadow said

Note: all versions of Firefox will force upload and does not matter the settings : Going back : unfortunately 56.0.2 and below is no longer safe to use for every day use do to secuity issues, but 52.5.0 ESR is. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ Note : Legacy Extensions will be deleted or removed in any version update after May 2018. You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles Please let us know if this solved your issue or if need further assistance.

Pkshadow, the 52 ESR doesn't support the extensions I would go to an older version FOR. So, there's no point to that.

Clearly, Mozilla would prefer I move to Chrome and Safari - something that, rationally, I should have done long ago.

20+ years advocating Mozilla and Firefox down the tubes.

Could have asked your questions in same thread vs having two similar.

Let's keep the invalid SSL certificate error discussion in /questions/1190846

So you never scrolled down a Extension page on addons.mozilla.org for the "Versions history > See complete version history" all these years?

For ColorfulTabs https://addons.mozilla.org/firefox/addon/colorfultabs/versions/

As you can then see there is Versions 31.2.3 and older that is for Firefox 52 to 56.