Cant upgrade on new iOS

Too high to remember what iOS Im using... but hey developers, Im trying to give you my money and support the app, (and upgrade my features) but when I tap "upgrade" in the about section, the app simply crashes.
Could you figure out a way to accept my money and upgrade the app? Ill rate 5 stars after. Thank you.

Super-Toaster about Frweed +, v6.0