Upgrade Coldfusion 11 to Coldfusion 2016 Migration Wizard login fails

I'm curious: is this on a Windows machine, using Internet Explorer? If so, try adding the domain of the URL you're using (even if it's localhost or 127.0.0.1) to the list of "trusted sites" in IE?  If you do that, then refresh the login page (so that it loads any javascript that may have been blocked), can you now login successfully?

If you cannot login, might you be able to try to use a different browser (even on the server, if that's where you're trying to login)?

And if you can't do that, then in IE you could try to use its Developer Tools feature (accessed via the function key F12), and look at its "network" tab, and enable that (hit the "play" icon/button) and watch the communications between the browser and the server, to see if any get a 404.

(And if you are using a browser other than IE when this login failure is happening, you may know that other browsers also offer such a "developer tools" feature, and it may be useful to check out the network tab and the request status codes there as well.)

Let us know if any of this helps.

(BTW, do beware that you should strive to get off of CF2016 as soon as you can. It got its last updates in March of this year. Now that CF2018 and 2021 got updates this month, there are security fixes in those which will NOT be rolled back to CF2016.)