Can anyone tell me why this error message appears on the payment page. I have just put paypal on the web site for the first time
Can you explain a little more about how/what you are trying to do.
What operations are you trying to do?
Are you using API calls?
Do you have a test site?
We have recently installed CS-Cart and are using the PayPal module to take payments. Our purchase testing crashes with this same error 'Security header not valid'. We contacted the CS-Cart support team and all they have told us to do is check the API Credentials. They provided some php (logs) but these mean little to us! Can any one help us resolve this error?