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Last updated: June 4, 2026
Returns from the DoExpressCheckoutPayment API.
Invalid PaymentAction: The PaymentAction parameter set to Authorization is not permitted when using unilateral (guest) checkout or non-credentialed authentication methods.
The payment process is halted, preventing the customer from finalizing their purchase. This can lead to a poor customer experience and potentially lost sales if the issue is not resolved promptly.
PaymentAction parameter: Ensure that the PaymentAction parameter is set to Sale instead of Authorization if you are using unilateral (guest) checkout. The Sale action is allowed for guest checkouts and does not require the user to have a PayPal account.$DoExpressCheckoutPayment = [
'TOKEN' => $token,
'PAYERID' => $payerId,
'PAYMENTREQUEST_0_PAYMENTACTION' => 'Sale',
'PAYMENTREQUEST_0_AMT' => '100.00',
'PAYMENTREQUEST_0_CURRENCYCODE' => 'USD'
];Authorization action, ensure that the user is authenticated and has a PayPal account. This means the user must log in to their PayPal account during the checkout process.PaymentAction parameter is set appropriately based on the type of checkout being used. Make sure that the parameter is not being changed or modified at any point before the API call.$DoExpressCheckoutPayment = [
'TOKEN' => $token,
'PAYERID' => $payerId,
'PAYMENTREQUEST_0_PAYMENTACTION' => 'Authorization',
'PAYMENTREQUEST_0_AMT' => '100.00',
'PAYMENTREQUEST_0_CURRENCYCODE' => 'USD',
];The NVP/SOAP API integration method is deprecated.
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