I have solved my problem by adding this code
context.RequestContext.HttpContext.Response.SuppressFormsAuthenticationRedirect = true;
in the class:
private class ChallengeResult : HttpUnauthorizedResult
{
public ChallengeResult(string provider, string redirectUri)
: this(provider, redirectUri, null)
{
}
public ChallengeResult(string provider, string redirectUri, string userId)
{
LoginProvider = provider;
RedirectUri = redirectUri;
UserId = userId;
}
public string LoginProvider { get; set; }
public string RedirectUri { get; set; }
public string UserId { get; set; }
public override void ExecuteResult(ControllerContext context)
{
// this line fixed the problem with returing null
context.RequestContext.HttpContext.Response.SuppressFormsAuthenticationRedirect = true;
var properties = new AuthenticationProperties() { RedirectUri = RedirectUri };
if (UserId != null)
{
properties.Dictionary[XsrfKey] = UserId;
}
context.HttpContext.GetOwinContext().Authentication.Challenge(properties, LoginProvider);
}
}
It fixed my problem with returning NULL.
Notice: don't use fiddler when logging with twitter authorization. You will receive error.