IPN Verification of payload requires that all keys and values are provided back to the VERIFY_URL. If any blank values are omitted, this will cause an otherwise valid payload to return 'INVALID' from the PayPal endpoint. Adding the 'keep_blank_values' argument will ensure that these elements will be added to the query string provided to PayPal to validate.
IPN Verification of payload requires that all keys and values are provided back to the VERIFY_URL. If any blank values are omitted, this will cause an otherwise valid payload to return 'INVALID' from the PayPal endpoint. Adding the 'keep_blank_values' argument will ensure that these elements will be added to the query string provided to PayPal to validate.