Possible Code Responses When Calling the API

Code	Description
0	Success
1	Payment exception
8000	Parameter validation error
8003	`content-type` must be `application/json`
8004	Request parameter format error, must be JSON
8007	Signature error
8011	Duplicate payment order number
8012	Invalid IP address
8013	Unsupported currency
8029	Merchant payment order number does not exist
8031	Order exception: No payment record
8033	Duplicate application not allowed
8034	Duplicate refund order number
8035	Already reached settlement account
8036	User is currently applying for a refund
8037	Current amount %S, minimum refund amount must be greater than 1 USD