Provider-hosted Apps debug error: The remote server returned an error: (401) unauthorised

Question

Hi,
Any help appreciated!!
I'm getting this error: "The remote server returned an error: (401) unauthorised when I debug a provider-hosted app.  I get the error on this line:  
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
See code below
I created a high trust development environment following the instructions provided here:
http://msdn.microsoft.com/en-us/library/office/fp179901(v=office.15).aspx and
http://msdn.microsoft.com/library/office/fp179923
I created a provider-hosted app with the intent to:
create a SharePoint list in the appweb
Use self-signed certificate, tokenhepler.cs and sharepointcontext.cs to retrieve current user context and access on SharePoint.  (No changes were made to tokenhelper.cs and sharepointcontext.cs)
retrieve list items from the SharePoint list in a button click event handler on a default.aspx of the remote web
What happens:
The app is deployed successfully to the Dev site
The SharePoint feature is deployed and activated
The default.aspx page of the remote web loads
The error (see image) is returned on clicking of the button
My environment is an on-premise SharePoint 2013 with AD and my dev box is standalone windows 8.1 running Visual Studio Professional 2013 Update 3.
The code block below is a copy of the default.aspx code-behind
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Microsoft.SharePoint.Client;
using Microsoft.IdentityModel.S2S.Tokens;
using System.Net;
using System.IO;
using System.Xml;
using System.Data;
using System.Xml.Linq;
using System.Xml.XPath;
namespace Idea.GeneratorWeb
public partial class Default : System.Web.UI.Page
SharePointContextToken contextToken;
string accessToken;
Uri sharepointUrl;
protected void Page_PreInit(object sender, EventArgs e)
Uri redirectUrl;
switch (SharePointContextProvider.CheckRedirectionStatus(Context, out redirectUrl))
case RedirectionStatus.Ok:
return;
case RedirectionStatus.ShouldRedirect:
Response.Redirect(redirectUrl.AbsoluteUri, endResponse: true);
break;
case RedirectionStatus.CanNotRedirect:
Response.Write("An error occurred while processing your request.");
Response.End();
break;
protected void Page_Load(object sender, EventArgs e)
//// The following code gets the client context and Title property by using TokenHelper.
//// To access other properties, the app may need to request permissions on the host web.
var spContext = SharePointContextProvider.Current.GetSharePointContext(Context);
//var spContext = new ClientContext("MySPDevInstance");
//spContext.Credentials = new NetworkCredential("username", "password");
//using (var clientContext = spContext.CreateUserClientContextForSPHost())
// clientContext.Load(clientContext.Web, web => web.Title);
// clientContext.ExecuteQuery();
// Response.Write(clientContext.Web.Title);
string contextTokenString = TokenHelper.GetContextTokenFromRequest(Request);
if (contextTokenString != null)
// Get context token
contextToken = TokenHelper.ReadAndValidateContextToken(contextTokenString, Request.Url.Authority);
// Get access token
sharepointUrl = new Uri(Request.QueryString["SPAppWebUrl"]);
accessToken = TokenHelper.GetAccessToken(contextToken, sharepointUrl.Authority).AccessToken;
// Pass the access token to the button event handler.
Button1.CommandArgument = accessToken;
protected void Button1_Click(object sender, EventArgs e)
// Retrieve the access token that the Page_Load method stored
// in the button's command argument.
string accessToken = ((Button)sender).CommandArgument;
if (IsPostBack)
sharepointUrl = new Uri(Request.QueryString["SPAppWebUrl"]);
// REST/OData URL section
string oDataUrl = "/_api/Web/lists/getbytitle('Diagrams In Idea Generator')/items?$select=Title,Diagram,SharingStatus";
// HTTP Request and Response construction section
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(sharepointUrl.ToString() + oDataUrl);
request.Method = "GET";
request.Accept = "application/atom+xml";
request.ContentType = "application/atom+xml;type=entry";
request.Headers.Add("Authorization", "Bearer " + accessToken);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
// Response markup parsing section
XDocument oDataXML = XDocument.Load(response.GetResponseStream(), LoadOptions.None);
XNamespace atom = "http://www.w3.org/2005/Atom";
XNamespace d = "http://schemas.microsoft.com/ado/2007/08/dataservices";
XNamespace m = "http://schemas.microsoft.com/ado/2007/08/dataservices/metadata";
List<XElement> entries = oDataXML.Descendants(atom + "entry")
.Elements(atom + "content")
.Elements(m + "properties")
.ToList();
var entryFieldValues = from entry in entries
select new
Character = entry.Element(d + "Title").Value,
Actor = entry.Element(d + "Diagram").Value,
CastingStatus = entry.Element(d + "SharingStatus").Value
GridView1.DataSource = entryFieldValues;
GridView1.DataBind();
Any ideas what I might be doing wrong

Answer 1

Hi ,
Use the below code
Public string GetAccessToken(){
string sharePointSiteUrlHost =  Page.Request["SPHostUrl"].Tostring();
string AccessToken = tokenHelper.GetS2SAccessTokenWithWindowsIdentity(sharePointSiteUrlHost, Request.LogonUserIdentity);
return accessToken;
Than initialize the ClientCOntext with the below Method
 private static ClientContext GetClientContextWithAccessTokenString(string targetUrl, object accessToken)
            ClientContext clientContext = new ClientContext(targetUrl);
            clientContext.AuthenticationMode = ClientAuthenticationMode.Anonymous;
            clientContext.FormDigestHandlingEnabled = false;
            clientContext.ExecutingWebRequest +=
                delegate(object oSender, WebRequestEventArgs webRequestEventArgs)
                    webRequestEventArgs.WebRequestExecutor.WebRequest.UserAgent = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)";
                    webRequestEventArgs.WebRequestExecutor.RequestHeaders["Authorization"] =
                        "Bearer " + accessToken;
            return clientContext;
use this clientCOntext and it will work.
Do not use
SharePointContextProvider
Whenever you see a reply and if you think is helpful,Vote As Helpful! And whenever you see a reply being an answer to the question of the thread, click Mark As Answer