Piotr Stulinski Piotr Stulinski - 1 month ago 55
ASP.NET (C#) Question

ASP.NET_SessionId + OWIN Cookies do not send to browser

I have a strange problem with using Owin cookie authentication.

When I start my IIS server authentication works perfectly fine on IE/Firefox and Chrome.

I started doing some testing with Authentication and logging in on different platforms and I have come up with a strange error. Sporadically the Owin framework / IIS just doesn't send any cookies to the browsers. I will type in a username and password which is correct the code runs but no cookie gets delivered to the browser at all. If I restart the server it starts working then at some point I will try login and again cookies stop getting delivered. Stepping over the code does nothing and throws no errors.

app.UseCookieAuthentication(new CookieAuthenticationOptions
AuthenticationMode = AuthenticationMode.Active,
CookieHttpOnly = true,
AuthenticationType = "ABC",
LoginPath = new PathString("/Account/Login"),
CookiePath = "/",
CookieName = "ABC",
Provider = new CookieAuthenticationProvider
OnApplyRedirect = ctx =>
if (!IsAjaxRequest(ctx.Request))

And within my login procedure I have the following code:

IAuthenticationManager authenticationManager = HttpContext.Current.GetOwinContext().Authentication;

var authentication = HttpContext.Current.GetOwinContext().Authentication;
var identity = new ClaimsIdentity("ABC");
identity.AddClaim(new Claim(ClaimTypes.Name, user.Username));
identity.AddClaim(new Claim(ClaimTypes.NameIdentifier, user.User_ID.ToString()));
identity.AddClaim(new Claim(ClaimTypes.Role, role.myRole.ToString()));
authentication.AuthenticationResponseGrant =
new AuthenticationResponseGrant(identity, new AuthenticationProperties()
IsPersistent = isPersistent

authenticationManager.SignIn(new AuthenticationProperties() {IsPersistent = isPersistent}, identity);

Update 1: It seems that one cause of the problem is when I add items to session the problems start. Adding something simple like
Session.Content["ABC"]= 123
seems to create the problem.

What I can make out is as follows:
1) (Chrome)When I login I get ASP.NET_SessionId + my authentication cookie.
2) I go to a page that sets a session.contents...
3) Open a new browser (Firefox) and try login and it does not receive an ASP.NET_SessionId nor does it get a Authentication Cookie
4) Whilst the first browser has the ASP.NET_SessionId it continues to work. The minute I remove this cookie it has the same problem as all the other browsers
I am working on ip address (10.x.x.x) and localhost.

Update 2: Force creation of
first on my login_load page before authentication with OWIN.

1) before I authenticate with OWIN I make a random
value on my login page to start the ASP.NET_SessionId
2) then I authenticate and make further sessions
3) Other browsers seem to now work

This is bizarre. I can only conclude that this has something to do with ASP and OWIN thinking they are in different domains or something like that.

Update 3 - Strange behaviour between the two.

Additional strange behaviour identified - Timeout of Owin and ASP session is different. What I am seeing is that my Owin sessions are staying alive longer than my ASP sessions through some mechanism. So when logging in:
1.) I have a cookied based auth session
2.) I set a few session variables

My session variables(2) "die" before the owin cookie session variable forces re-login, which causes unexpected behaviour throughout my entire application. (Person is logged in but is not really logged in)

Update 3B

After some digging I saw some comments on a page that say the "forms" authentication timeout and session timeout need to match. I am thinking normally the two are in sync but for whatever reason the two are not in sync.

Summary of Workarounds

1) Always create a Session first before authentication. Basically create session when you start the application
Session["Workaround"] = 0;

2) [Experimental] if you persist cookies make sure your OWIN timeout / length is longer than your sessionTimeout in your web.config (in testing)


I have encountered the same problem and traced the cause to OWIN ASP.NET hosting implementation. I would say it's a bug.

Some background

My findings are based on these assembly versions:

  • Microsoft.Owin, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35
  • Microsoft.Owin.Host.SystemWeb, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35
  • System.Web, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a

OWIN uses it's own abstraction to work with response Cookies (Microsoft.Owin.ResponseCookieCollection). This implementation directly wraps response headers collection and accordingly updates Set-Cookie header. OWIN ASP.NET host (Microsoft.Owin.Host.SystemWeb) just wraps System.Web.HttpResponse and it's headers collection. So when new cookie is created through OWIN, response Set-Cookie header is changed directly.

But ASP.NET also uses it's own abstraction to work with response Cookies. This is exposed to us as System.Web.HttpResponse.Cookies property and implemented by sealed class System.Web.HttpCookieCollection. This implementation does not wrap response Set-Cookie header directly but uses some optimizations and handful of internal notifications to manifest it's changed state to response object.

Then there is a point late in request lifetime where HttpCookieCollection changed state is tested (System.Web.HttpResponse.GenerateResponseHeadersForCookies()) and cookies are serialized to Set-Cookie header. If this collection is in some specific state, whole Set-Cookie header is first cleared and recreated from cookies stored in collection.

ASP.NET session implementation uses System.Web.HttpResponse.Cookies property to store it's ASP.NET_SessionId cookie. Also there is some basic optimization in ASP.NET session state module (System.Web.SessionState.SessionStateModule) implemented through static property named s_sessionEverSet which is quite self explanatory. If you ever store something to session state in your application, this module will do a little more work for each request.

Back to our login problem

With all these pieces your scenarios can be explained.

Case 1 - Session was never set

System.Web.SessionState.SessionStateModule, s_sessionEverSet property is false. No session id's are generated by session state module and System.Web.HttpResponse.Cookies collection state is not detected as changed. In this case OWIN cookies are sent correctly to the browser and login works.

Case 2 - Session was used somewhere in application, but not before user tries to authenticate

System.Web.SessionState.SessionStateModule, s_sessionEverSet property is true. Session Id's are generated by SessionStateModule, ASP.NET_SessionId is added to System.Web.HttpResponse.Cookies collection but it's removed later in request lifetime as user's session is in fact empty. In this case System.Web.HttpResponse.Cookies collection state is detected as changed and Set-Cookie header is first cleared before cookies are serialized to header value.

In this case OWIN response cookies are "lost" and user is not authenticated and is redirected back to login page.

Case 3 - Session is used before user tries to authenticate

System.Web.SessionState.SessionStateModule, s_sessionEverSet property is true. Session Id's are generated by SessionStateModule, ASP.NET_SessionId is added to System.Web.HttpResponse.Cookies. Due to internal optimization in System.Web.HttpCookieCollection and System.Web.HttpResponse.GenerateResponseHeadersForCookies() Set-Cookie header is NOT first cleared but only updated.

In this case both OWIN authentication cookies and ASP.NET_SessionId cookie are sent in response and login works.

More general problem with cookies

As you can see the problem is more general and not limited to ASP.NET session. If you are hosting OWIN through Microsoft.Owin.Host.SystemWeb and you/something is directly using System.Web.HttpResponse.Cookies collection you are at risk.

For example this works and both cookies are correctly sent to browser...

public ActionResult Index()
        .Response.Cookies.Append("OwinCookie", "SomeValue");
    HttpContext.Response.Cookies["ASPCookie"].Value = "SomeValue";

    return View();

But this does not and OwinCookie is "lost"...

public ActionResult Index()
        .Response.Cookies.Append("OwinCookie", "SomeValue");
    HttpContext.Response.Cookies["ASPCookie"].Value = "SomeValue";

    return View();

Both tested from VS2013, IISExpress and default MVC project template.