为什么这个cookie有时会为空？

Question

I have a very strange problem that has been giving me trouble for weeks now. I have an ASP.NET page that gets a value from a cookie like so

string SessionKey = Request.Cookies["SessionKey"].Value;

The cookie itself is set from within a silverlight application running on the same server, using a little helper method I found here on SO.

public static void SetCookie(string key, string value)
{
   DateTime expiration = DateTime.UtcNow + TimeSpan.FromDays(5);
   string cookie = String.Format("{0}={1};expires={2}", key, value, expiration.ToString("R"));
   HtmlPage.Document.SetProperty("cookie", cookie);
}

So here's the issue. I have three computers. All three are in separate locations (house, office, different office). One is a development machine with this whole web application hosted on it. The second is a web server with a copy of the web application running in IIS. The third is just a plain computer in an office.

On the dev machine, testing against its own localhost dev environment, this works fine and the cookie is what I expect.

On the dev machine, talking to the server, it also works fine. The cookie is what it should be, etc etc.

The third, plain computer, when I connect to the server, I have a null cookie. Doesn't work!

BUT on the third, plain computer, when I connect to the dev machine (I made it public facing to test this), it works fine and the cookie is populated.

All three of these machines are on completely separate networks.

This issue is not restricted to the third machine, there are lots of machines that, when they talk to the server, the cookie isn't working, but does work if they try to view my dev setup. Even stranger, every now and then it DOES work, but very inconsistently. Any ideas what would be causing this?

Answer 1

Things to check

• cookies path, just add it as "{0}={1};expires={2};path=/;"
• if server name has only alphanumeric characters (no underscore or other special characters); try to use IP address rather than the domain/server name or vice versa
• if cookies could be set from test aspx-page

You can use Fiddler to see if you can get more insight into this.