Not passing AJAX requests?

Question

AJAX

Good day. Error when trying to send AJAX request in console: jquery-2.1.4.min.js:4 Mixed Content: The page at ' https://*****.com/cargo/calc-temp/ ' was loaded over HTTPS , but requested an insecure XMLHttpRequest endpoint ' http://****.com/cargo/handler.php '. This request has been blocked; the content must be served over HTTPS.
There are no problems on the local computer.
Request:

$.ajax({
       type: "POST",
       url: "handler.php",
       data: form_data,
       success: function(response) {

       },
       error: function(response) { 
        alert('Error');
       }
     });

I tried to change the url to relative, full, with http, https - nothing helped.

Answer 1

If the main site is loaded via https, then all resources must be requested via a secure protocol, so the link to handler.php must be with https. Actually, this is indicated by the error:

This request has been blocked; the content must be served over HTTPS

Answer 2

set up CORS on the server

Answer 3

The problem was in htaccess