In shopware 5, while ordering with the Paypal payment method. Redirecting to the Paypal login page sometimes shows an error message "Security error. Security header is not valid". If we reload the page or try again to order with Paypal it does not show the error and is redirected to the Paypal login page.
My Question is Why sometimes does it show the error message?
If the error is intermittent, it's a programming or system error in retrieving its configuration.
The "security header is not valid" is returned by PayPal when the API credentials used in a request are missing, invalid, or for an incorrect environment (sandbox vs. live).