I submitted my last macOS application with IAP on Oct. 23rd, 2025. I was able to test-purchase a non-consumable product with the StoreKit configuration file at that time. These days, every time I test a new macOS application with the configuration file, a purchase process fails. The thing is they all now fail if I test the store with existing applications that were once working. Xcode shows the following debugging error.
Purchase failed with error: systemError(Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service created from an endpoint was invalidated from this process." UserInfo={AMSDescription=An unknown error occurred. Please try again., AMSURL=http://localhost:53272/WebObjects/MZBuy.woa/wa/inAppBuy, NSDebugDescription=The connection to service created from an endpoint was invalidated from this process., AMSStatusCode=200, AMSServerPayload={
All my iOS apps don't exhibit the same problem. This StoreKit fiasco only happens for macOS applications. And I'm thinking that it all started to occur after I began using Xcode 26. Not a single line of code has changed. But the applications that were once able to process IAP all now fail. And I'm suspecting that it's Xcode 26 that is responsible for this failure. My Xcode version is 26.2, by the way. Any macOS application developer experiencing the same problem?