Fix for OpenCart Error: The security header is not valid
I've been working with OpenCart for the past couple days and ran into a problem that had many posts on the Internet with no solutions in my searches. So if you a problem with the PayPal Express Checkout in OpenCart, you may find a solution below.
The error on checkout was always this: "The security header is not valid"
What I did to solve this in the OpenCart Administration:
- In System > Users > APIs: Deleted the API user.*
- In Extensions > Payments, Uninstalled Paypal Express Checkout.
- Reinstalled Express Checkout.
- Re-entered the Paypal API info.
* Although in my case, I started with deleting the API user, I don't think it was actually necessary. I'd skip step 1 as a test if you have that problem.