To check if session is available or not

I tried some code in Application_Error like this

Session["mysession"] = "Some message";

but the problem is sometimes session is not available in Application_Error. So I want to check whether s开发者_开发知识库ession is available or not.

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Session doesn't always exist within the context of the current Application_Error. Try the following:

protected void Application_Error(object sender, EventArgs e)
{
    if (Context.Handler is IRequiresSessionState || 
        Context.Handler is IReadOnlySessionState)
    {
         // Session exists
         Session["mysession"] = "Some message";
    }
}