Prompt illegal transactions, cardholder authentication failure, transactions not supported by the issuing bank, etc. Generally, your credit card is restricted by the risk control of the banking system. The banking system thinks you are cashing in, which limits your transaction.

First, risk control is also graded.

Primary risk control: occasionally swipe your card.

It used to work all the time, but suddenly it doesn't work, which means that the banking system already thinks you belong to a risk household. So occasionally, I will fail to swipe my card, and sometimes I can brush it out!

Intermediate risk control: the card is not good, but the code can be scanned.

No matter how you swipe your card, you can't swipe 100, but you can scan the code. At this time, it is better to change the machine mainly with a code scanning brush.

Ultimate risk control: swipe the card to scan the code.

That means that the system has the highest risk control level for you, and you can't brush it as frequently as before. Either don't use this card, or change to a machine that can brush!