Error logging into Yahoo from Firefox

Greetings, After a recent Firefox update, I can no longer login to my Yahoo account in a normal window. I can sign in to Yahoo from a private Firefox window, using Chrome in both regular and private windows, as well as Safari regular and private windows. I have cleared cache and cookies for all Yahoo websites, restarted Firefox and my Mac, no joy. I have checked that I have the most up to date version of Firefox. Since I can login from a private Firefox window, and all other browsers' windows, there is clearly something on Firefox's end causing this breakdown when using Firefox's standard browsing. When trying to login, I can get to Yahoo's sign-in page, several ways (logged out and tried logging in), I type in my username, click Next and it spins for 15 seconds then immediately shows an error message in a new window. The error message is shown below: An error occurred while processing your request. Reference #97.8e09c617.1794211833.68184b03 https://errors.edgesuite.net/97.8e09c617.1794211833.68184b03 I have also tried logging into different Yahoo, AT&T and Google accounts, they all work fine except for my legacy sbcglobal account username, which is what I need to use for my Fantasy Football - this same username works on other browsers so it is not an AT&T/Yahoo issue. I am using Chrome now as I cannot manage Fantasy Football in a private window. Please advise a fix for this. Thanks Tracy