I tried that but it did not work. Then I manually deleted all the SVTP cookies and it still did not work. Then I found this discussion on a Xenforo forum. My saved bookmarks were for http:// and not https://
I tried https:// and then I was able to get the user login / password prompt via Chrome.
XF 2.1 - Cookies are required to use this site error message
Several of my members have reported an issue when they click the login button. They just get this error message instead: Clearing their cookies seemed to fix the issue for a little while, but it's come back for them. Does anybody know what might be causing this?xenforo.com
Good catch, I've added a redirect from http to https, that should clear up the problem for anyone else.