I was messing around with different settings and directions, just trying to see if something could help to work it out. I looked through iPhone, iPad, and finally went back to Mac. Here is my solution:
- Instead of opening App Store, go to System Settings.
- Click your name (Apple ID) > Media & Purchases > Account > Manage.
- It opens up App Store. Enter your password. You should see "Account Settings". It's different from what you get when you click "Account Settings" directly in App Store.
- Edit your billing information as normal.



That cryptic error message is not very helpful. You will never know what is going on behind it.