When I try to sign-in, I’m immediately taken to a Yahoo page tat says “Sorry, the page you requested cannot be found”

I'm signing in (using RoboForm) to: login.live.com . This takes me to the sign-in page and my Username and Password are filled in. But instead of then opening my Inbox, a get a Yahoo page telling my the page cannot be found. Then it goes back to my (Yahoo) Home page. I can access my Inbox by entering: https://blu178.mail.live.com . Did the URL change?