You say 'upgrade' but you need to renew the 'update service' and click a different button. I made that error last time and this required a new installation and serial number. Fortunately, it got sorted. Whether there's a difference between the upgrade and renewal prices right now, I don't know.

My XDP comes up for renewal pretty soon as well and I'm not sure yet if I'll go along because the price is ridiculously high for what you get (based on last year's updates and upgrade to v. 15 -- which was mainly a nuisance). These renewals and upgrades seem to finance their new pet project, the Cloud app, rather than the serious development of the desktop apps.