One of the answers on forums gave me some ideas and I was able to fix this. We are still using Objective-C and StoreKit 1 with ancient SKPayment. The issue was in several UIWindows we have in hierarchy, the last UIWindow was created to present some kind of HUD and didn't have rootViewController. Once I commented out HUD presentation and ended up with only one valid and fully configured UIWindow with rootViewController purchase process works again. Also had before fix 'Could not find a UI anchor for com.xxxx purchase'