Getting Error when verifying merchant

I want to integrate an apple pay account on the website, but on the point where I am validating merchant that return "false" responses . I already followed the documentation and tried many times but still did not resolve it. Please help me to resolve this issue. so that i can integrate apple pay for heartland.

here i mentioned my block of code where i am verifying merchant, please help to fix this.

server side code: (PHP):

$merchantSession = fetchAppleMerchantSession($validationURL);
echo json_encode($merchantSession);

function fetchAppleMerchantSession($validationUrl){
    $cert_url = base_path('cert/merchant.pem');
    $cert_key = base_path('cert/merchant.key');
    
    $data = [
        'merchantIdentifier' => 'domain.com',
        'domainName' => 'domain.com',
        'displayName' => 'Disp Name',
        'initiative' => 'web',
        'initiativeContext' => 'domain.com'
    ];
    
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $validationUrl);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
    curl_setopt($ch, CURLOPT_CERTINFO, true);
    curl_setopt($ch, CURLOPT_VERBOSE, true);
    curl_setopt($ch, CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1_2);
    curl_setopt($ch, CURLOPT_SSLCERT, $cert_url);
    curl_setopt($ch, CURLOPT_SSLKEY, $cert_key);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/json"));
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    
    $res = curl_exec($ch);
    curl_close($ch);
    
    $result = json_encode($res);
    return ['data' => $result, 'status' => false];
}

client side code (JS):

// Create Apple Pay session within the user gesture handler
        const session = new ApplePaySession(6, paymentRequest);

        // Handle merchant validation
        session.onvalidatemerchant = (event) => {
                console.log("event", {event, session});
                const validationURL = event.validationURL;

                fetch('gp_applepay_validate.php', {
                        // Replace with your server-side validation endpoint
                        method: 'POST',
                        headers: {
                            'Content-Type': 'application/json',
                            'Access-Control-Allow-Headers': "*"
                        },
                        body: JSON.stringify({
                            validationURL
                        }),
                    })
                    .then((response) => {
                        console.log("response.json()", response);
                        return response.json();
                    })
                    .then((data) => {
                        console.log("datappp", data);
                        
                        if (data.status) {
                            event.completeMerchantValidation(data.data);
                        } else {
                            console.error('Merchant validation failed:', data.data);
                            session.abort();
                            alert('Payment failed: ' + data.data); // Improve error message
                        }
                    })
                    .catch((error) => {
                        console.error('Error during merchant validation:', error);
                        session.abort();
                        alert('An error occurred during payment. Please try again later.'); // Generic error message for user
                    });
        };