ReCaptcha Request contains an invalid argument - recaptcha

Question

I am implementing Google reCaptcha Enterprise.
So far I am sending the request and getting back the token. But when I send the token with curl to create the assessment I am getting this error:
object(stdClass)#2 (1) {
["error"]=>
object(stdClass)#1 (3) {
["code"]=>
int(400)
["message"]=>
string(37) "Request contains an invalid argument."
["status"]=>
string(16) "INVALID_ARGUMENT"
}
}
I am not sure why.
My curl request looks like this:
$token = $_POST['g-recaptcha-response'];
//echo "Token: " . $token;
$data = [
'event' => [
'token' => $token,
'siteKey' => RECAPTCHAKEY,
'expectedAction' => 'LOGIN'
]
];
echo 'data<br>' . json_encode($data);
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_POST, true);
//curl_setopt($verify, CURLOPT_POSTFIELDS, http_build_query($data));
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
$headers = array(
"Content-Type: application/json; charset=utf-8",
);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data));
$response = curl_exec($curl);
curl_close($curl);
$responseData = json_decode($response);
echo '<pre>';
var_dump($responseData);
echo '</pre>';
The response that I am getting from google look like this (a little bit shortened):
data
{"event":{"token":"03AD1IbLACZr43YilgAgGSblh6cauhQmv9hic-hm7yPCApL-cFwth7MDaWvVKaIIf3fOiKsku7KbnL7VXArw3sbMuSQ0gpdEPhxAYrvAOOdT2kEE2uE9HBf_jTnk896LeK8Ae3Zj1ZHHMm2N-75v0jv-AB6faye77gM-6-KaiwAsS7X6_skfV_xE-VuPMOXhHf0HARnRi7DJm5aYaafxjoAj54RH7t-xbqQc_IDFUvVAAm8uGmoKpXTrweOFrrsh3SfekYJRYWZzBWlT1z0fGTdbeOrHcVTKaRY9wSEIFYubrKmYweQDLngx5x5d5oFAk0stHGPQojPLxDoUh6hSeglyorHJwjZkd3aervNoi_bz1ymP2fI24lg7jXSaIdqTU2YrwVKrnl2X6McNcKVAMS7I6Bnflsf-6_2mLCU2LzK68qUNrFfad6L0pQZn-twSiSjfhvpdctbAVqlMkUsZgqFjEn7zsC8iycMcUUHCOFxxlWMMth5RZ4e55CLAX3Hdmm27pzbe7OYDCjqGkLZgDNYxieLIXWH0ww88B5G5A39vpkLr0SMX396jWMJns7GKh8mNg3dzpl18R2-9t_rZsxyGrxRwCBAoDzvSsU39n-gj4SwXYUDRksj7n9OBMIN5Md-eQaCcKAh7XpvIQDe3-LVVukqi1vigm6KL2ZxZiqg0L-_M7KxJC7Sex7T5gqA4WMvGhfq1tHtneWTuVZs8T0ogIddcFBb4jHyfYc6g91aPCU6EiHnW-bm63qTc8g_oDOe6iITjKQQZAar5xPlLcowJdG780Ti_d2aFqSUSF6cM4T1AYxuwkgvyn89J2QcP0dlETyXqqGj7M4hk7ID9GY04B-q9CFFONegIe3VFCqj7xEdXBMDUpMdLTFHfE5UtTYmaZdSuC2NWvxVnx-UUoWCMXEE4lGgpayM6jVFcSW4PEJK2m656St6i7kTtJQivc9m2f3nToot1LkS1qvNKENvuA-RF9fP8WI4-fHByFa0-BoYEPmiW7tJ-_qD-gwm6_jczpdV2fu8di1y6C3GcpolAE8GqhH7nBHwsCHPeXIiOp6XIFobBrmKB42JT4XQS2_Ba2wIMhICnrAqVkmwADSjym9C1P--CntQopjgIWT9vDIvtLd67zdeMl2LRZOJtcWvwebYzxwSwZmZuxnjgXe6NU1GKhqsGfyoa7SqJ1PVkknw2W9bRRlS-ko32TtWE3slaMxL4qbbg7JX78iPg8f5Jhb2jM8kPhziCoEyCTsMOjugjTyLFx8uCXPDdxwqZdUQKuh4OEzUqJK7I4q7adTZ38fegPp2XLrm69yTPYxhqehniYiAU_wmvIXr1z3TYbj2sFvPyfUgzsbL0fVOmKd0w11xWKiFYHZTdpkPN7NMowmWfPd1CFoS2Pfd3nbIC5BOnUX","siteKey":"123456789ABCDE","expectedAction":"LOGIN"}}
I have no "expected action" set up on the form page.
I just have a form with two text fields and a button.
<form id="login-form" method='post' action='src/recaptcha.php' name='login-form'>
...
<button class="g-recaptcha btn btn-primary"
data-sitekey="<?php echo RECAPTCHAKEY; ?>"
data-callback='onSubmit'
data-action='submit'><?php echo $lan->getValue('login'); ?></button>

Answer 1

Posting an answer for better community visibility.
OPs issue resolved with the help of google/cloud-recaptcha-enterprise.
Creating an assessment by sending a request to the reCAPTCHA Enterprise API. You can use either the gcloud CLI or API key for authentication. Please see here for more information.