title: reCAPTCHA v3 - Error: No reCAPTCHA clients exist
body: <p>First of all, I am aware that the same problem was already discovered here:
  <a href="https://stackoverflow.com/questions/53875281/error-no-recaptcha-clients-exist-recaptcha-v3">Error: No reCAPTCHA clients exist (reCAPTCHA v3)</a> But since the answers there, didn't lead me to a solution, I try my luck here.</p>
  
  <hr>
  
  <p>So I tried using reCAPTCHA, since I get alot of spam mails from the form on my webpage. In my HTML head I have that code:</p>
  
  <pre><code>&lt;script src="https://www.google.com/recaptcha/api.js?render=MY_SITE_KEY"&gt;&lt;/script&gt;
  &lt;script&gt;
  grecaptcha.ready(function() {
    grecaptcha.execute("MY_SITE_KEY").then(function(token) {
      console.log(token);
    });
  });
  &lt;/script&gt;
  </code></pre>
  
  <p>to load the Captcha and which generates a token. When I submit my form, I call the following ajax code:</p>
  
  <pre><code>$.ajax({
    type: 'POST',
    url: $(form).attr('action'),
    data: {
      name: name,
      email: email,
      message: message,
      captcha: grecaptcha.getResponse()
  }).done(function(response){ ... })
  </code></pre>
  
  <p>and finally in PHP I do the following:</p>
  
  <pre><code>&lt;?php
  
    $secret = "MY_SECRET_KEY";
    $response = $_POST["captcha"];
    $verify=file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret={$secret}&amp;response={$response}");
    $captcha_success=json_decode($verify);
  
      if ($captcha_success-&gt;success==false) {
        echo "reCaptcha indentified you as a bot. We don't like bots here.";
      }
      else if ($captcha_success-&gt;success==true) {
  
        // MY WHOLE mail() function here
  
      }
  
  ?&gt;
  </code></pre>
  
  <p>When I submit the form then, I get the error:</p>
  
  <pre><code>Uncaught Error: No reCAPTCHA clients exist.
      at Gw (recaptcha__de.js:511)
      at Object.Q5 [as getResponse] (recaptcha__de.js:519)
      at HTMLFormElement.&lt;anonymous&gt; (main.js:265)
      at HTMLFormElement.dispatch (jquery.min.js:3)
      at HTMLFormElement.q.handle (jquery.min.js:3)
  </code></pre>
  
  <p>What have I done wrong? I followed Googles instructions, but maybe I missed something.</p>