It seems that when I attempt to make PayPal Card Payments online. It says the following: Security header is not valid
This is both on Live Mode and Test Mode.
Any ideas?
It seems that when I attempt to make PayPal Card Payments online. It says the following: Security header is not valid
This is both on Live Mode and Test Mode.
Any ideas?
There are already topics for this: Error: Security header is not valid, Paypal sandbox not working? Payment failed. Please try again. Security header is not valid, Guest link pay now button shows a blank page