In Azure WebRole always GetExternalLoginInfoAsync is null when Multiple instances

Question

I am using a external authentication (Google y Microsoft) in mvc Project (vb.NET). It is work good when i use only one instance in Azure. But when i use multi instances always fail (return null) but I see than the urls are correct. I use a MachineKey in web.config pero it is not solve nothing. I am using a classic web role.

In development or with a single instance it works. If I put more than one instance it always fails (except if I was authenticated with an instance, in that case the authentication still works)

I only use external cookie, since I only need to determine that they have been authenticated, but not save their identity in a local authentication cookie

    Public Sub ConfigureAuth(app As IAppBuilder)

    app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie)

    Dim options = New MicrosoftAccountAuthenticationOptions With {
            .ClientId = "CLIENID",
            .ClientSecret = "SECRET",
            .CallbackPath = New PathString("/signinMS")
        }
    app.UseMicrosoftAccountAuthentication(
            options
            )


    app.UseGoogleAuthentication(New GoogleOAuth2AuthenticationOptions() With {
            .ClientId = "CLIENTID",
            .ClientSecret = "SECRET"
        })

End Sub

Example function callback (where is the error)

        <AllowAnonymous>
    Public Async Function ExternalLoginCallback() As Task(Of ActionResult)
        Dim loginInfo = Await AuthenticationManager.GetExternalLoginInfoAsync()

        If loginInfo Is Nothing Then
            Return Redirect("/")
        End If

        Request.GetOwinContext().Authentication.SignOut(HttpContext.GetOwinContext().Authentication.GetAuthenticationTypes().Select(Function(o)
                                                                                                                                        Return o.AuthenticationType
                                                                                                                                    End Function).ToArray())

        Return Redirect("/Areatrabajo")

    End Function

Image Redirects

PROBLEM FOUND

Found the problem. Increasing Web Role instances in azure changes the machineKey. For this reason, I cannot use the authentication cookies of the other instances.