In addition to having an Adobe ID from a supported country you must also provide payment from a financial institution located in a supported country. Please make sure that the credit card you are trying to use has a billing address in a supported country. If you continue to have trouble upgrading please let me know.
I tried to pay using ukrainian IP and error appeard before entering any card data. Maybe it's because of IP-address? Now I have another situation. I click on "Subscribe now" button and get new error "Error in your order".