Unsubscribe error message
I figured it out with the help of the back trace from the error.

It was the CiviAlerts extension which I had installed apparently, I really liked this CiviAlerts too because it let me give my mail admins a message window to see when I wanted all of them to do something differently (like use a different smart group for example in a mailing).

Anyway I just went in and turned off that Extension then redid my test and guess what?  The form showed up with the email (and a few asterisks) and a confirmation page.  Problem solved.  Thanks for the assistance.

The changes described in this Pull Request for the CiviAlerts extensions should resolve the issue: https://github.com/mr-vara/me.vara.civialerts/pull/1