Can’t add credit card to App Store

Hello blythe273,

I know with some apps and updates, you are required to have a payment method on file. Not being able to add a payment method can be frustrating. I would say to first make sure the credit card you are trying to add is an accepted method of payment for your region. Here's where you can check: Payment methods that you can use with your Apple ID

Also, make sure you're following the correct procedures for changing your payment method. Here's a guide you can look over: Change, add, or remove Apple ID payment methods

Best regards!