Required oauth_verifier parameter not provided asp.net c#

Question

i am facing this error, right now in oauthusing linq to twitter library:

<?xml version="1.0" encoding="UTF-8"?> 
<hash> 
<error>Required oauth_verifier parameter not provided</error> 
<request>/oauth/access_token</request> 
</hash> 

i have followed this documentation link: https://linqtotwitter.codeplex.com/wikipage?title=Implementing%20OAuth%20for%20ASP.NET%20Web%20Forms&referringTitle=Learning%20to%20use%20OAuth to implement the OAuth process, I get the this error at following line: await auth.CompleteAuthorizeAsync(new Uri(twitterCallbackUrl));

below is the full code, please help me on this:

AspNetAuthorizer auth;
    string twitterCallbackUrl = "http://127.0.0.1:58192/Default.aspx";

    protected async void Page_Load(object sender, EventArgs e)
    {
        auth = new AspNetAuthorizer
        {
            CredentialStore = new SessionStateCredentialStore
            {
                ConsumerKey = ConfigurationManager.AppSettings["consumerKey"],
                ConsumerSecret = ConfigurationManager.AppSettings["consumerSecret"]
            },
            GoToTwitterAuthorization =
                twitterUrl => Response.Redirect(twitterUrl, false)
        };

        if (!Page.IsPostBack && Request.QueryString["oauth_token"] != null)
        {
            __await auth.CompleteAuthorizeAsync(new Uri(twitterCallbackUrl));__

            // This is how you access credentials after authorization.
            // The oauthToken and oauthTokenSecret do not expire.
            // You can use the userID to associate the credentials with the user.
            // You can save credentials any way you want - database, isolated 
            //   storage, etc. - it's up to you.
            // You can retrieve and load all 4 credentials on subsequent queries 
            //   to avoid the need to re-authorize.
            // When you've loaded all 4 credentials, LINQ to Twitter will let you 
            //   make queries without re-authorizing.
            //
            var credentials = auth.CredentialStore;
            string oauthToken = credentials.OAuthToken;
            string oauthTokenSecret = credentials.OAuthTokenSecret;
            string screenName = credentials.ScreenName;
            ulong userID = credentials.UserID;

            //Response.Redirect("~/Default.aspx", false);
        }
    }

    protected async void AuthorizeButton_Click(object sender, EventArgs e)
    {
        await auth.BeginAuthorizeAsync(new Uri(twitterCallbackUrl));
        //await auth.BeginAuthorizeAsync(Request.Url);
    }

Answer 1

The problem occurs because your custom URL doesn't include the parameters that Twitter returned after the application requested authorization. If you set a breakpoint on CompleteAuthorizationAsync and type Request.Url into the Immediate window, you'll see these parameters:

If you still want to manually specify your URL, you need to include these parameters. Here's one way to do that:

    string completeOAuthUrl = twitterCallbackUrl + Request.Url.Query;
    await auth.CompleteAuthorizeAsync(completeOAuthUrl);

Alternatively, you can just use the page URL because that will already contains the proper parameters:

    await auth.CompleteAuthorizeAsync(Request.Url);