Hello team, It'd be very grateful if you give us some advice for our issue. It's about receipt verification in production environment. Details are as follows. User tried to purchase consumable IAP in production environment. Price is charged for IAP. After that, tried to verify receipt using the receipt of the transaction, but it failed with an error message. "21004 The shared secret you provided does not match the shared secret on file for your account." This error occurs only sometimes, not always. Most of purchase succeeded without this issue. For your reference, we've sold subscription IAP but now stopped to sell subscription IAP since last year. And we've been transferred this app from other iOS team last year. Our iOS developer account have configured both primary shared secret and app-specific shared secret for this app. I've found the similar issue with ours. https://forums.developer.apple.com/forums/thread/746202 Thank you. Best regards