I also found this problem from this Monday morning, in the sandbox environment, resume the purchase operation, if the product is an in-app purchase non-consumable item, you can get the corresponding historical bill, but if it is an automatic subscription product, it is difficult to receive the historical bill, resulting in the inability to restore the automatic subscription product. You'll need to try a few or even 10 times to restore your purchase before you can get your previous bill. Resuming a purchase shows an error with the error Error Domain=SKErrorDomain Code=0 "An unknown error has occurred". I hope that Apple can check whether there is a related problem with the corresponding sandbox billing server, and I am anxious to wait for this problem to be solved.