Disabling 'User Script Sandboxing' under the Project's Build Settings > Build Options fixed the issue for me as well! Thanks!

I have the same issue: <SKPaymentQueue: 0x282460b00>: Payment completed with error: Error Domain=ASDServerErrorDomain Code=3502 "This item is not available." UserInfo={storefront-country-code=USA, client-environment-type=Sandbox, AMSServerErrorCode=3502, NSLocalizedFailureReason=This item is not available.} I tried using a random product ID to see if the ID was wrong but in that case, the ASDServerErrorDomain Code is 3504...so this rules out issues with the product ID.. Any advice would be greatly appreciated!

I had the same issue and this resolved it: rm -rf ~/Library/Developer/Xcode/DerivedData/ rm -rf ~/Library/Caches/CocoaPods/ pod deintegrate pod update