And a flowchart.

Payment process can be divided into back-end process and front-end process.

According to experience, signature error is an error in xml encryption.

The following is the original xml for submitting a unified order.

Let's be clear here: Spbill _ create _ IP and notify _ URL are not the cause of signature error even if they are written dead.

Check the merchant information, that is, the merchant number mch_id and the merchant's key (here, it is necessary to pay attention to the key, which is the key in the email sent by Tencent to the applicant after applying for WeChat payment successfully, and an operation certificate is required for this key to take effect).