Headers not sent when making a cURL/PHP request over HTTPS

This is because HTTPS requires exchanging and verify the SSL cert which protects the URL so if you hit an HTTPS URL you will receive an error because you aren’t handling the security translation.

// Initialize session and set URL.
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);

// Set so curl_exec returns the result instead of outputting it.
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    
// Get the response and close the channel.
$response = curl_exec($ch);
curl_close($ch);

Will generate this error:

Failed: Error Number: 60. Reason: SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

You can mitigate this with an insecure setting update, just add this line before calling curl:

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

Otherwise you need to set CURLOPT_CAINFO to a CA certificate authority that should be trusted.

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_CAINFO, getcwd() . "path/to/trusted/cert");

Hard to tell because we have absolutely no idea how you’re using Curl.