Hi,

The issue here is being caused by user input, since the button code allows user to enter most values the data entered could be incorrect if there are no checks before sending to PayPal. e.g.

- the user can enter amounts like "$100.00", the "$" symbol would cause an issue

- User can enter their own ZIP and state, which if not correct would cause the issue. 

Essentially you would need to put in checks to ensure that data entered by customers is valid before sending it to PayPal.com