Error in remote proxy while processing transaction: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.storekitd"

I am working on a billing implementation in UnityIAP.
Recently, when I press the billing button on iOS, I get an Unknown error the first time,
I checked the logs and found the following error.

<SKPaymentQueue: 0x2823b65c0>: Error in remote proxy while processing transaction: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.storekitd" UserInfo={NSDebugDescription=connection to service named com.apple.storekitd}\

Special conditions,
When this is occurring, addTransactionObserver is being called after the purchase order.
If addTransactionObserver is called for a paymentQueue during the purchase process, would this error be called?

Or if there is any problem on the AppleStore side, I would appreciate it if you could let me know.
Thank you in advance.