What is SKErrorDomain Error 0 and what can I do about it?

Debugging StoreKit errors, particularly SKErrorDomain Error 0 or SKError.Code.unknown, can be challenging as they often stem from unknown issues within Apple's API. These errors typically indicate a problem on Apple's side, especially if the app was functioning correctly before. Developers are advised to start by checking the RevenueCat status page, which is frequently updated with information about any issues with Apple's or Google's APIs, followed by Apple’s developer system status page. If no widespread issues are detected, testing with StoreKit configuration files in a simulator can help identify whether the problem lies within the app’s code or configuration. If everything works with the configuration file, developers should verify their App Store Connect setup, ensuring that the bundle ID and product identifiers match, and that all products are in the correct status. It is also essential to confirm that all agreements and tax forms are up to date in App Store Connect. Additionally, resetting the test environment by deleting the app from the simulator or creating a new sandbox test account may resolve any corrupted testing states. Ultimately, many of these errors may result from temporary issues in Apple's backend, particularly within the sandbox environment used by App Review, and may be resolved by resubmitting the app once Apple addresses the issue.