Thank you for your reply! I was surprised because I thought there was one originaltransactionid per subscription. In this document, it is written as follows. This value is the same for all receipts that have been generated for a specific subscription https://developer.apple.com/library/archive/releasenotes/General/ValidateAppStoreReceipt/Chapters/ReceiptFields.html#//apple_ref/doc/uid/TP40010573-CH106-SW1 Is it correct to refer to the above information? However, do not assume that the value will remain unchanged for the lifetime of a subscription.The documentation does not indicate what may cause the originaltransactionid to change Are there other IDs that can be used to identify if a user has already purchased a same subscription?

Thanks to your answer I understand that the originaltransactionid does not change between upgrades and downgrades of the same subscription group. I have one more question.For example, suppose you have the following subscription groups and subscriptions: ex) subscription-group-asubscription-a-1 subscription-a-2 subscription-group-bsubscription-b-1 subscription-b-2 I would like to know when the user takes the following actions. Purchase subscription-a-1 -> (A) Cancel subscription-a-1 Purchase subscription-b-1 Repurchase subscription-a-1 -> (A`) At this time, do A and A` have the same originaltransactionid?

I had the same problem. In my case, I use 3 TextFields. The first and second use .name for the TextField type, and the third specifies .password. In this case, changing the TextField type from .name to .username solved the problem. I still don't understand why .name causes problems. I still don't understand why .name causes problems. I'm glad if you can use it as a reference.