I did implemented the OKTA authentication in VB.NET application. It's successfully redirecting to the Okta Site, getting authenticated. But When I check with the Request.IsAuthenticated, its always false. Because of that my application hitting OKTA again and again. Please refer my startup class below

<Assembly: OwinStartup(GetType(FacilityRevocationManagement.Startup))>

Namespace FacilityRevocationManagement

  Public Class Startup

    Private ReadOnly _clientId As String = ConfigurationManager.AppSettings("okta:ClientId")

    Private ReadOnly _redirectUri As String = ConfigurationManager.AppSettings("okta:RedirectUri")

    Private ReadOnly _authority As String = ConfigurationManager.AppSettings("okta:OrgUri")

    Private ReadOnly _clientSecret As String = ConfigurationManager.AppSettings("okta:ClientSecret")

    Public Sub Configuration(ByVal app As IAppBuilder)

      System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12

      IdentityModelEventSource.ShowPII = True

      app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType)

      ConfigureAuth(app)

    End Sub

    Public Sub ConfigureAuth(ByVal app As IAppBuilder)

      app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie)

      app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType)

      app.UseCookieAuthentication(New CookieAuthenticationOptions())

      app.UseOpenIdConnectAuthentication(New OpenIdConnectAuthenticationOptions With {

      .ClientId = _clientId,

      .ClientSecret = _clientSecret,

      .Authority = _authority,

      .RedirectUri = _redirectUri,

      .ResponseType = OpenIdConnectResponseType.CodeIdToken,

      .Scope = OpenIdConnectScope.OpenIdProfile,

      .TokenValidationParameters = New TokenValidationParameters With {

        .NameClaimType = "name"

      },

      .Notifications = New OpenIdConnectAuthenticationNotifications With {

      .AuthorizationCodeReceived = Async Function(n)

                       Dim tokenClient = New TokenClient($"{_authority}/v1/token", _clientId, _clientSecret)

                       Dim tokenResponse = Await tokenClient.RequestAuthorizationCodeAsync(n.Code, _redirectUri)

                       If tokenResponse.IsError Then

                         Throw New Exception(tokenResponse.[Error])

                       End If

                       Dim userInfoClient = New UserInfoClient($"{_authority}/v1/userinfo")

                       Dim userInfoResponse = Await userInfoClient.GetAsync(tokenResponse.AccessToken)

                       Dim claims = New List(Of Claim)(userInfoResponse.Claims) From {

                 New Claim("id_token", tokenResponse.IdentityToken),

                               New Claim("access_token", tokenResponse.AccessToken)

                             }

                       n.AuthenticationTicket.Identity.AddClaims(claims)

                     End Function

        }

      })

    End Sub

  End Class

This function used to check whether user authenticated

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    If Not IsPostBack Then

      If Not Request.IsAuthenticated Then

        HttpContext.Current.GetOwinContext().Authentication.Challenge(New AuthenticationProperties With {

          .RedirectUri = "/FacilityRevocationManagement/View/Welcome.aspx"

        }, OpenIdConnectAuthenticationDefaults.AuthenticationType)

      End If