You should not downgrade to older versions of Firefox, they are not secure and have known issues. What issues are you having with the most recent version of Firefox?

As I mentioned - I need to use the S3 plugin for my work.

I don't like any of the other alternatives out there for ftp to AWS

It is not supported in Quantum --

Which add-on are you trying to use?

S3 Organizer

It looks like that add-on has been abandoned by it's author. I'd suggest you try to find a new way to manage your S3

Well, thanks. It's not like I haven't been trying to do that.

As usual, Firefox is at the bottom of the pack, at least it seems like that's what they have been trying to accomplish for quite a while.

Any reason not using a stand alone FTP Program like everyone used to ....and still do........... Like Filezilla https://filezilla-project.org/

What about this idea:

Get a previous version of FF using this program . . . [Link to external download tool removed by Admin]

Use the old version of FF, "just" for the program that needs it . . . They're kept available, for some reason. Probably this.

Then, use the latest version of FF to browse, and have the latest security features needed.

I have tried stand alones - they either don't work or work poorly.

I deleted Quantum and re-installed an older version. All set and back to work with S3 Organizer for time being. Thanks for responses.