any external hyperlink (to Firefox) does not open in Firefox. Firefox is default browser. Firefox opens but does not open external hyperlink.
If I click on a hyperlink in application that is external to Firefox, clicking on the link opens Firefox, goes to the home page and that is all. The hyperlinked web page does not open.
If Firefox is already open, a new browser window is opened, goes to the home page. The hyperlinked web page does not open.
Apparently this is an add-on problem. I disabled all of the add-ons and the problem is now fixed. I have not been able to find out which is the culprit yet but I will track it down. If and when I find the problem add-on, I will post the name(s) here.