Unable to connect to my online site collection using c# console application

Question

I have the following console application to connect to my online site:-

using Microsoft.SharePoint.Client;
using System;
using System.Linq;
using System.Security;
using System.Linq;
using System.Text;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            string siteCollectionUrl = "https://***.sharepoint.com";
            string userName = "***@***.com";
            string password = "T*****";
            Program obj = new Program();
            try
            {
                obj.ConnectToSharePointOnline(siteCollectionUrl, userName, password);
            }
            catch (Exception ex)
            {
                string msg = ex.Message.ToString();

            }

        }

        public void ConnectToSharePointOnline(string siteCollUrl, string userName, string password)
        {

            //Namespace: It belongs to Microsoft.SharePoint.Client
            ClientContext ctx = new ClientContext(siteCollUrl);

            // Namespace: It belongs to System.Security
            SecureString secureString = new SecureString();
            password.ToList().ForEach(secureString.AppendChar);

            // Namespace: It belongs to Microsoft.SharePoint.Client
            ctx.Credentials = new SharePointOnlineCredentials(userName, secureString);

            // Namespace: It belongs to Microsoft.SharePoint.Client
            Site mySite = ctx.Site;

            ctx.Load(mySite);
            ctx.ExecuteQuery();

            Console.WriteLine(mySite.Url.ToString());
        }
    }
}

now the user i am trying to login with have 2 factor authentication enabled. so when i run the application, i got this exception "The sign-in name or password does not match one in the Microsoft account system" although i am passing valid username and password .. any idea?

Answer 1

Your account may be MFA (Multi-factor authentication) enabled! With MFA enabled, the method using class SharePointOnlineCredentials with username and password for authentication would not work.

You have only two options: Use user credentials with the OTP prompt or call. This needs to install the package SharePointPnPCoreOnline: https://www.nuget.org/packages/SharePointPnPCoreOnline.

 var authManager = new OfficeDevPnP.Core.AuthenticationManager();  
 // This method calls a pop up window with the login page and it also prompts  
 // for the multi factor authentication code.  
 ClientContext ctx = authManager.GetWebLoginClientContext(siteUrl);

Use app-only for authentication: https://docs.microsoft.com/en-us/sharepoint/dev/solution-guidance/security-apponly-azureacs

Answer 2

This blog post describes how to register an app with Azure Active Directory (Azure AD), how to authenticate with Azure AD using the Microsoft Authentication Library (MSAL) to get an access token, an then how to use that access token to make SharePoint Client Object Model (CSOM) calls.

Calling SharePoint Online APIs using Azure AD App-Only permissions and certificate auth

I don't think the blog post calls this out, but you will need two Nuget packages to use the code shown in the blog post:

https://www.nuget.org/packages/Microsoft.Identity.Client/

https://www.nuget.org/packages/Microsoft.SharePointOnline.CSOM/

var token = await TokenProvider.GetAccessTokenAsync(new Uri(siteUrl).GetLeftPart(UriPartial.Authority));
 
using var context = new ClientContext(siteUrl);
context.ExecutingWebRequest += (sender, e) =>
{
    e.WebRequestExecutor.RequestHeaders["Authorization"] = "Bearer " + token;
};
 
context.Load(context.Web, web => web.Title);
await context.ExecuteQueryAsync();