Cors Header 'Access-Control-Allow-Origin' Missing

Question

I'm calling this function from my asp.net form and getting following error on firebug console while calling ajax.

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at . (Reason: CORS header 'Access-Control-Allow-Origin' missing).

var url= '
        $.ajax({
            url: url,
            crossOrigin: true,
            type: 'GET',
            xhrFields: { withCredentials: true },
            accept: 'application/json'
        }).done(function (data) {
            alert(data);                
        }).fail(function (xhr, textStatus, error) {
            var title, message;
            switch (xhr.status) {
                case 403:
                    title = xhr.responseJSON.errorSummary;
                    message = 'Please login to your server before running the test.';
                    break;
                default:
                    title = 'Invalid URL or Cross-Origin Request Blocked';
                    message = 'You must explictly add this site (' + window.location.origin + ') to the list of allowed websites in your server.';
                    break;
            }
        });

I've done alternate way but still unable to find the solution.

Note: I've no server rights to make server side(API/URL) changes.

Accepted Answer

This happens generally when you try access another domain's resources.

This is a security feature for avoiding everyone freely accessing any resources of that domain (which can be accessed for example to have an exact same copy of your website on a pirate domain).

The header of the response, even if it's 200OK do not allow other origins (domains, port) to access the ressources.

You can fix this problem if you are the owner of both domains:

Must Read

Solution 1: via .htaccess

To change that, you can write this in the .htaccess of the requested domain file:

    <IfModule mod_headers.c>
    Header set Access-Control-Allow-Origin "*"
    </IfModule>

If you only want to give access to one domain, the .htaccess should look like this:

    <IfModule mod_headers.c>
    Header set Access-Control-Allow-Origin '
    </IfModule>

Cors Header 'Access-Control-Allow-Origin' Missing

8 Answers

Must Read

Solution 1: via .htaccess

Marcus Vance