.net Session state has created a session id but cannot save it because the response has already been dropped by the application

Question

.net Session state has created a session id but cannot save it because the response has already been dropped by the application

I have below in my global.asax Session_Start

string myBrowser = Utils.SafeUserAgent(Request);
foreach (string bannedbrowser in BrowserBan.BrowsersToBan)
{
   if (myBrowser.IndexOf(bannedbrowser, StringComparison.OrdinalIgnoreCase) > -1)
   {
       HttpContext.Current.Response.Redirect("/bannedBrowser.htm");
       Session.Abandon();
       break;
   }

This prevents access to the transcoder on my site. but every now and then I get the error

System.Web.HttpException: Session state has created a session id, but cannot
  save it because the response was already flushed by the application.
    at System.Web.SessionState.SessionIDManager.SaveSessionID(
      HttpContext context, String id, Boolean& redirected, Boolean& cookieAdded)
    at System.Web.SessionState.SessionStateModule.CreateSessionId()
    at System.Web.SessionState.SessionStateModule.DelayedGetSessionId()
    at System.Web.SessionState.SessionStateModule.ReleaseStateGetSessionID()
    at System.Web.SessionState.SessionStateModule.OnReleaseState(Object source,
      EventArgs eventArgs)
    at System.Web.SessionState.SessionStateModule.OnEndRequest(Object source,
      EventArgs eventArgs)
    at System.Web.HttpApplication.SyncEventExecutionStep.System.Web
      .HttpApplication.IExecutionStep.Execute()
    at System.Web.HttpApplication.ExecuteStep(IExecutionStep step,
      Boolean& completedSynchronously)

It only happens when I try to access it via (for example) Google Transcoder, but I want to understand why this is happening and how I can prevent it.

I need to drop the session so that the user agent is re-evaluated on upgrade.

+2

c # global-asax

nLL 24 Sep 09 at 16:37

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2 answers

Robert Claypool · Answer 1 · 2009-09-24T16:59:18+0000

Have you seen this stream ?

I ran into this exception (in a different context) and fixed it like this:

void Session_Start(object sender, EventArgs e) 
{
string id = Session.SessionID;
}

JustLoren · Answer 2 · 2009-09-24T16:54:57+0000

Have you tried to reverse the order of session abandonment or redirection?

Session.Abandon();
HttpContext.Current.Response.Redirect("/bannedBrowser.htm", true);

.net Session state has created a session id but cannot save it because the response has already been dropped by the application

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