An error had ocurred: <br />HTTP Status: 400:<br />Error message:<br />&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
&lt;error xmlns=&quot;http://checkout.google.com/schema/2&quot; serial-number=&quot;8b484330-3c4d-432a-87db-cb2de322fb9a&quot;&gt;
  &lt;error-message&gt;Carts must contain at least one item.&lt;/error-message&gt;
&lt;/error&gt;