1. Merchant does not support credit card payment. Although many merchants also support WeChat payment, if you pay merchants by scanning the code, you can only use a savings card, not a credit card, because scanning the code is equivalent to transferring money, and credit cards cannot transfer money.

2. The available amount is insufficient, and the credit card can only be consumed when the available amount is sufficient. If your credit card has no available amount, or the amount of goods is greater than your payment amount, the merchant will scan your payment code with a code scanner, and the payment fails because the amount is insufficient.