Access_Token after successful authentication in Azure AD using OWIN

There are several reasons why you might be getting a null access token and null properties in context.ProtocolMessage even after following the provided code. Check you've replaced "your-client-id" and "your-tenant-id" with the actual values from your Azure Active Directory (AAD) application registration.

Hi Abhishek, Thank you for your response. I have used the below code provided by you but still I am getting accessToken as null. Infact all the properties coming under context.ProtocolMessage are null. 

Here's how you can capture the access token in your ASP.NET WebForms application:
 

1. Install the necessary NuGet packages:

Install-Package Microsoft.Owin.Security.OpenIdConnect
Install-Package Microsoft.Owin.Security.Cookies

        2. Configure OWIN middleware in your Startup.cs file:

using Microsoft.Owin;
using Microsoft.Owin.Security;
using Microsoft.Owin.Security.Cookies;
using Microsoft.Owin.Security.OpenIdConnect;
using Owin;

[assembly: OwinStartup(typeof(YourNamespace.Startup))]

namespace YourNamespace
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType);
            app.UseCookieAuthentication(new CookieAuthenticationOptions());
            
            app.UseOpenIdConnectAuthentication(new OpenIdConnectAuthenticationOptions
            {
                ClientId = "your-client-id",
                Authority = "https://login.microsoftonline.com/your-tenant-id",
                RedirectUri = "https://yourwebsite.com/signin-oidc",
                ResponseType = "id_token",
                Scope = "openid",
                TokenValidationParameters = new System.IdentityModel.Tokens.TokenValidationParameters
                {
                    ValidateIssuer = false // You may want to change this depending on your requirements
                },
                Notifications = new OpenIdConnectAuthenticationNotifications
                {
                    SecurityTokenValidated = context =>
                    {
                        // Here you can capture the access token
                        var accessToken = context.ProtocolMessage.AccessToken;
                        // You can store it in session, database, etc.
                        return Task.FromResult(0);
                    },
                    RedirectToIdentityProvider = context =>
                    {
                        // This is where you can add additional parameters
                        if (context.ProtocolMessage.RequestType == OpenIdConnectRequestType.Authentication)
                        {
                            // Add parameters here if needed
                        }
                        return Task.FromResult(0);
                    }
                }
            });
        }
    }
}

           3. In your code-behind file or wherever you need to use the access token, you can retrieve it from the session or wherever you stored it:

protected void Page_Load(object sender, EventArgs e)
{
    var accessToken = Session["AccessToken"] as string;
    // Use the access token as needed
}