Authorize.net returned a malformed response, aborted.

[jointsystems]

What triggers this response "Authorize.net returned a malformed response, aborted." We are getting this error message on some 16 prestashops that were processing orders earlier this month Sept. 2019 in prestashop ver 1.6.1.24?

if (!isset($response[7]) || !isset($response[3]) || !isset($response[9]))

{
$msg = 'Authorize.net returned a malformed response for cart';
if (isset($response[7]))
$msg .= ' '.(int)$response[7];
Logger::addLog($msg, 4);
die('Authorize.net returned a malformed response, aborted.');
}

[jointsystems]

Error log from usengines.org

thrown in /home/usenginescorp/public_html/usengine.org/modules/amzpayments/controllers/front/amzpayments.php on line 342

line 342 $physical_destination = $reference_details_result_wrapper->GetOrderReferenceDetailsResult->getOrderReferenceDetails()