Example 1: has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.
response.setHeader("Access-Control-Allow-Origin", "*");
response.setHeader("Access-Control-Allow-Credentials", "true");
response.setHeader("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
response.setHeader("Access-Control-Allow-Headers", "Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers");
Example 2: javascript access to xmlhttprequest at from origin 'null' has been blocked by cors policy
//Open the HTML file using live server, it will work
Example 3: allow cross origin
Access-Control-Allow-Origin: *
Access-Control-Allow-Origin:
Access-Control-Allow-Origin: null
Example 4: javascript cors error
$.ajax({
headers: { "Accept": "application/json"},
type: 'GET',
url: 'http://cl.ly/2wr4',
crossDomain: true,
beforeSend: function(xhr){
xhr.withCredentials = true;
},
success: function(data, textStatus, request){
console.log(data);
}
});
Example 5: Angular Laravel has been blocked by CORS policy: Request header field x-requested-with is not allowed by Access-Control-Allow-Headers in preflight response.
namespace App\Http\Middleware;
use Closure;
class Cors
{
public function handle($request, Closure $next)
{
$response = $next($request);
$response->header('Access-Control-Allow-Methods', 'HEAD, GET, POST, PUT, DELETE');
$response->header('Access-Control-Allow-Headers', $request->header('Access-Control-Request-Headers'));
$response->header('Access-Control-Allow-Origin', '*');
return $response;
}
}
Example 6: Access to XMLHttpRequest at 'http://localhost/MySQL_pracs/InsertUser.php' from origin 'http://localhost:4200' has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.
//Access to XMLHttpRequest at 'http://localhost/[api path].php' from origin 'http://localhost:4200' has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.
//The error is simply saying that "Content-Type" is missing from "Access-Control-Allow-Headers".
//Therefore we need to add "Content-Type" to "Access-Control-Allow-Headers".