Persistent cookie not working in Internet Explorer

Question

I have a problem with persistent cookies in Internet Explorer, that is, I can set the cookies, but cannot make them persist. I'm using Internet Explorer 11, and have tried "Internet Options" -> "Advanced" -> "Reset", but it didn't help.

I've written this test code:

class Program {
    public static void Main(string[] args) {
        HttpListener listener = new HttpListener();
        listener.Prefixes.Add("http://+:7777/");
        listener.Start();

        ThreadPool.QueueUserWorkItem((o) = > {
            while (listener.IsListening) {
                ThreadPool.QueueUserWorkItem((c) = > {
                    HandleRequest(c as HttpListenerContext);
                }, listener.GetContext());
            }
        });

        Console.Write("Press any key to quit . . . ");
        Console.ReadKey(true);
        listener.Stop();
        listener.Close();
    }

    static void HandleRequest(HttpListenerContext ctx) {
        var cookie = ctx.Request.Cookies["TestCookie"];

        if (cookie == null) {
            Console.WriteLine("Setting cookie...");
            var expiryDate = DateTime.UtcNow.AddDays(360);
            ctx.Response.Headers["Set-Cookie"] = "TestCookie=some_value; Path=/; Expires=" + expiryDate.ToString("ddd, dd-MMM-yyyy H:mm:ss") + " GMT; HttpOnly";
        } else {
            Console.WriteLine("Cookie: " + cookie);
        }
        ReturnString(ctx, "OK");
    }

    protected static void ReturnString(HttpListenerContext ctx, String s) {
        try {
            byte[] buf = Encoding.UTF8.GetBytes(s);
            ctx.Response.ContentLength64 = buf.Length;
            ctx.Response.OutputStream.Write(buf, 0, buf.Length);
        } catch (Exception e) {

        } // suppress any exceptions
        finally {
            // always close the stream
            ctx.Response.OutputStream.Close();
        }
    }
}

Now, when accessing 127.0.0.1:7777, I first get "Setting cookie", and then "Cookie: TestCookie=some_value" on all subsequent requests. In Chrome the cookie is persistent (I can close the browser, restart it, and still get "Cookie: TestCookie=some_value"), but this doesn't work in Internet Explorer. That is, when using IE, I get the "Setting cookie" on the first request every time I restart the browser. So the cookie is clearly not there anymore.

Why is this? Am I doing something wrong? Surely there must be some way to set persistent cookies in IE using a C# server?

Answer 1

Hm, I found the answer. It's quite embarrasingly simple, really. When setting expiry date, I used the code

expiryDate.ToString("ddd, dd-MMM-yyyy H:mm:ss")

but of course this creates a localized representation of the date. And since I'm in Norway, the "ddd" created the day of the week in norwegian. And of course IE was not able to parse that.

This simple change solved the problem:

expiryDate.ToString("ddd, dd-MMM-yyyy H:mm:ss", System.Globalization.CultureInfo.InvariantCulture)

So sorry for all your trouble, folks..