auth_code

This parameter indicates the payment code of a user. The payment code of a WeChat user is composed of f 18 digits. Codes beginning with 10-14 are for users in mainland China and support Cross-Border Pay. Codes beginning with 15 are for users in Hong Kong, which are available only in China Hong Kong and China mainland.

A payment code is valid for 1 minute, and the payment code will automatically refresh if it expires and becomes invalid after it’s used.

In offline status, 15 payment codes are cached in the WeChat app for users in poor network conditions. However, this scenario is only applicable if password verification is not required.

openid

Openid is the unique identifier of a WeChat ID under a certain appid. It’s an encrypted identification string of a user. Openid varies for different WeChat IDs under the same appid, while it also varies for the same WeChat ID under different appid.

The institution can use this parameter to identity a user and verify whether the users of different orders are the same person. In addition, the merchant can link a user's openid to its own account system to fetch user information.

This parameter is mandatory for Official Account Payment and Mini Program Payment.

notify_url

When calling the Unified Order Placement API, the institution needs to pass the notify_url (callback notification address) parameter, so as to receive callback notifications after a payment is completed.

notify_url must be the real address of the merchant system, rather than an example address in the API document or demo.

notify_url must be a complete full path beginning with "https://" or "http://", and must contain an externally accessible domain name or IP address. Local domain names or private network IP addresses such as localhost, 127.0.0.1, and 192.168.x.x are not supported.

notify_url must not carry any parameter.

Example of common errors: