502 Bad Gateway - Sendgrid PHP Mail Issue - php

Question

I am getting 502 Bad Gateway error when I try to send email using Sendgrid's PHP library. I have attached the error log below,
502 Array (
[0] => HTTP/1.1 502 Bad Gateway
[1] => Server: nginx
[2] => Date: Thu, 27 Dec 2018 19:30:14 GMT
[3] => Content-Type: text/html
[4] => Content-Length: 166
[5] => Connection: keep-alive
[6] => Access-Control-Allow-Origin: https://sendgrid.api-docs.io
[7] => Access-Control-Allow-Methods: POST
[8] => Access-Control-Allow-Headers: Authorization, Content-Type, On-behalf-of, x-sg-elas-acl
[9] => Access-Control-Max-Age: 600
[10] => X-No-CORS-Reason:
https://sendgrid.com/docs/Classroom/Basics/API/cors.html
[11] =>
[12] => )
I don't know where I am wrong and I followed as per the documentation in SendGrid's website (Github as well). I have attached the code below what I used.
I have already tried possible troubleshooting found in other questions and issues in the GitHub repository of sendgrid-php.
<?php
require("sendgrid/sendgrid-php.php");
$email = new \SendGrid\Mail\Mail();
$email->setFrom("noreply#mydomain.com", "Leads");
$email->setSubject($_POST['school'] . " - Appointment");
$tos = [
"support#mydomain.com" => "Support",
$_POST['email'] => $_POST['name']
];
$email->addTos($tos);
$email->addContent("text/html", "<p><strong>Name:</strong> {$_POST['name']}</p>");
$email->addContent("text/html", "<p><strong>Email:</strong> {$_POST['email']}</p>");
$email->addContent("text/html", "<p><strong>Mobile:</strong> {$_POST['mobile']}</p>");
$email->addContent("text/html", "<p><strong>School:</strong> {$_POST['school']}</p>");
$email->addContent("text/html", "<p><strong>Count:</strong> {$_POST['count']}</p>");
$email->addContent("text/html", "<p><strong>Gender:</strong> {$_POST['gender']}</p>");
$sendgrid = new \SendGrid('xxxxxxxxxxxxxxAPIKEYxxxxxxxxxxxxxxxx');
try {
$response = $sendgrid->send($email);
print $response->statusCode() . "\n";
print_r($response->headers());
print $response->body() . "\n";
} catch (Exception $e) {
echo 'Caught exception: '. $e->getMessage() ."\n";
}
?>
The email should be sent when the code is executed.

Answer 1

There is some weird issue with SendGrid. Sometimes, the API gets soft deleted automatically in the backend. To make the code work, I had to create a new API key and retry. And the solution worked.
Note - Some issues in GitHub instructed to initialize a constructor with a from address, but that was not the actual issue.
The workaround is to create a new API key in the dashboard till
SendGrid investigates why the API is soft deleted so that the API call
returns an error.