Rated 5 out of 5 stars

by Firefox user c7f95a on Nov. 18, 2017 ·

Latest version of Firefox 57 doesn't support this.
So I changed my version to March 20178, Version 52 by going to
https://ftp.mozilla.org/pub/firefox/releases/
Go down the page until you find version 52. Then for your operating system
Then directories by Language, I use EN US (English USA)
Then Right Click and Save-AS
Now install version 52. It should replace the broken version 57
Version 52 was from March 2017, it works great.
Then STOP AUTOMATIC UPDATES that is an item in the PREFERENCES
In MAC it's under the FireFox name, in Windows I think it's under the FIle Manu

Look for the AUTOMATIC UPDATES which defaults to ON, and TURN IT OFF !!

I do NOT like Automatic Updates by default. So just fix it by turning it off.

Then you will find FireFTP is one of Tools Menu, Extensions

It restored my saved FTP Server settings

Jeff, Orange County, CA