cors error in php code example

Example 1: header cros orgin using php

<?php
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Headers: *");
...

Example 2: php strict-origin-when-cross-origin

header("Access-Control-Allow-Origin: *");

Example 3: php cors error

Access-Control-Allow-Headers does not allow * as accepted value, see the Mozilla Documentation here.

Instead of the asterisk, you should send the accepted headers (first X-Requested-With as the error says).