AJAX上传大文件不起作用

I am developing MVC application. I want to upload file with ajax post method,

 $.ajax({
            type: 'POST',
            url: '@Url.Action("Add", "Media")',
            data: formData,

            contentType: false,
            processData: false,
            success: function (data) {
                var result = JSON.parse(data);
                if (result.Status !== 200) {

                    toastr.error('@Resources.Resource.Error_Unexpected');
                    return;
                }

                if (result.Result === "SUCCEED") {
                    toastr.success('@Resources.Resource.SuccessUpload');
                    window.location.reload();



                    return;
                } else {
                    toastr.error('@Resources.Resource.Error_Unexpected');
                }

            },
            error: function (error) {
                console.log(error);
                toastr.error('@Resources.Resource.Error_Unexpected');
                return;
            }
        });
    }

It works with small file. But when I try to upload 90MB pdf file it doesn't goes to controller. What is the problem. Thanks in advance.

In your web.config file you need to increase maximum upload file setting. It affects the entire application.

<configuration>
  <system.web>
    <httpRuntime maxRequestLength="xxx" />
  </system.web>
</configuration>

You need to place value in KB. The default is 4096 (= 4 MB).