dwsnc

Can I upgrade a CO award ticket on UA metal? When I checked my reservation on the UA website, it gave me the opportunity to "modify" my reservation to both economy + or to business (this is a TATL). I cannot get it to accept a one way request (outgoing) to business, but I was able to get economy + on the return.

Is upgrading to business on an X fare not allowed? If so, why is the option presented?

Thanks in advance