Why did I get API error code 10415?
PayPal returned API error code 10415 - The transaction was refused because of an invalid argument.
The DoExpressCheckoutPayment API returns this error if a successful transaction has already completed for the Express Checkout token.
Here's how to resolve this issue:
- Use the GetExpressCheckoutDetails API with the same token to get transaction information, including the Transaction ID.
- Use the TransactionSearch API to find the transaction.
- If the transaction was created with an Invoice ID, use the Invoice ID as a parameter to the TransactionSearch API, or you can limit the search to a specific date and time range.