In App Purchase

21000 The App Store could not read the JSON object you provided.

21002 The data in the receipt-data property was malformed.

21003 The receipt could not be authenticated.

21004 The shared secret you provided does not match the shared secret on file for your account.

21005 The receipt server is not currently available.

21006 This receipt is valid but the subscription has expired. When this status code is returned to your server, the receipt data is also decoded and returned as part of the response.

21007 This receipt is a sandbox receipt, but it was sent to the production service for verification.

21008 This receipt is a production receipt, but it was sent to the sandbox service for verification.