This article has a link to an official Mozilla server with ALL past Firefox releases: Install an older version of Firefox.

Now that security updates have stopped for Firefox 52 ESR, you should start planning for migration by looking at the new session management extensions that have been released over the past year. They do work differently because in Firefox 57+, extensions can't create their own folders and files outside of the storage features offered to extensions.

Thank you; I understand looking for new extensions. Do you happen to know the "highest" version of ESR that I can go to that still works with Session Manager? I don't recall/have a record of what version of ESR I was using, unfortunately. Was just guessing it was 52.

From the page you supplied, I only see version 59, so I next clicked on "Directory of other versions and languages" - do I simply click on one of those listed "esr" versions to begin the download?

Thanks again for your reply and help.

The Firefox 52 ESR series ends with 52.9.0esr.

Now, I should mention that Firefox 60 profiles are not easily downgraded to Firefox 55 or earlier. You may lose history and your legacy add-ons may be locked out (not able to be re-enabled). You'll need to search around for advice on addressing that if you proceed with downgrading.

Thanks for all the info, jscher2000. I'm in for some fun, I see. Technology is both a blessing and a curse!

My new motto is the same as the old motto; "think it through before you click." Oh, and of course, the same goes for: "save your work and backup often."

Maybe you'd be interested in this :

https://chefkochblog.wordpress.com/2018/01/31/firefox-replacement-for-session-manager/

https://addons.mozilla.org/en-US/firefox/addon/my-sessions/?src=recommended

And this thread :

https://www.reddit.com/r/firefox/comments/70hfpw/webextention_alternative_for_session_manager/

Thanks, McCoy! Your links might help me figure out/narrow down what I can use as an alternative, especially if my downgrade "fails" and locks me out of using the Session Manager extension. Fingers crossed that the downgrade works/accepts the old profile, etc. I truly would like my historical sessions back before I have to compromise on a new method that I am guessing won't be as robust and easy.

Helpme1 said

I truly would like my historical sessions back before I have to compromise on a new method that I am guessing won't be as robust and easy.

It's never easy to let go of something you were used to, something that worked for you, something you were happy with. But sometimes moving on to something different may pleasantly surprise you and even make you wish that you had found it before .....

On the one hand I hope that your downgrade won't fail and that you can hold on to your Session Manager, but on the other hand : using the latest Firefox version would be so much better in many ways .....

Whatever you do : wishing you the best of luck  !

Thank you, McCoy - I'll try to adopt that positive outlook.  :o)

Also just found and used https://www.jeffersonscher.com/res/scrounger.html to extract one of my old session's set of links and it's great to know that's out there, I might extract them all first and then downgrade. It will be time consuming to extract them all, but worth the peace of mind.

I'm guessing that is jscher2000's tool, so thanks very much for that, too, jscher2000! You're a life saver.

Note that Firefox 52 is NOT supported, nor safe to use anymore. It has known security holes and should not be used on the internet. Please update to Firefox 60 or later ASAP

Thanks, Tyler, I know that security is an issue with older versions. I'll do my best to get over the loss of Session Manager and try some of the alternatives and/or sadly, a different browser, if necessary, however, I am extremely disappointed like many others that it is no longer available.

https://ftp.mozilla.org/pub/firefox/releases/52.9.0esr/win64/en-US/

Busca el firefox 48

Helpme1 said

Thank you; I understand looking for new extensions. Do you happen to know the "highest" version of ESR that I can go to that still works with Session Manager? I don't recall/have a record of what version of ESR I was using, unfortunately. Was just guessing it was 52. From the page you supplied, I only see version 59, so I next clicked on "Directory of other versions and languages" - do I simply click on one of those listed "esr" versions to begin the download? Thanks again for your reply and help.