ASHX ile çalışırken session null geliyorsa ve bir türlü session’a erişemiyorsanız IReadOnlySessionState’i implement edin:

C#

public class Sertifika : IHttpHandler, System.Web.SessionState.IReadOnlySessionState
{
     public void ProcessRequest (HttpContext context)
     {
           context.Response.ContentType = "text/plain";
           context.Response.Write(context.Session["isil"]);
     }
     public bool IsReusable
     {
            get
            {
                  return false;
            }
     }
}

VB:

Public Class Sertifika
Implements System.Web.IHttpHandler
Implements SessionState.IReadOnlySessionState

Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
     context.Response.ContentType = "text/plain"
     context.Response.Write(context.Session("isil"))
End Sub
ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
     Get
          Return False
     End Get
End Property

End Class