Index was outside the bounds of the array.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IndexOutOfRangeException: Index was outside the bounds of the array.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[IndexOutOfRangeException: Index was outside the bounds of the array.]
System.Collections.Generic.List`1.Add(T item) +37
Site.Core.OnSessionStart(HttpSessionState s, HttpRequest r) +67
Site.Application.Session_Start() +53

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor) +0
System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments) +87
System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) +101
System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) +21
System.Web.Util.ArglessEventHandlerProxy.Callback(Object sender, EventArgs e) +56
System.Web.SessionState.SessionStateModule.RaiseOnStart(EventArgs e) +9976119
System.Web.SessionState.SessionStateModule.CompleteAcquireState() +160
System.Web.SessionState.SessionStateModule.BeginAcquireState(Object source, EventArgs e, AsyncCallback cb, Object extraData) +1095
System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +254
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

    

    public class Core
    {
        List<SessionEnvironment>            _Environments;
    
        private Core(HttpApplication a, RouteCollection routes)
        {
            _Environments            = new List<SessionEnvironment>();
        }

        public void OnSessionStart(HttpSessionState s, HttpRequest r)
        {

            SessionEnvironment env = new SessionEnvironment(_Site, _GeoIPService, s, r);
            s["environment"] = env;
            _Environments.Add(env);
        }

using System;
using System.Collections.Generic;
using System.Threading;

namespace ConsoleApp1
{
    class Program
    {
        static void Main()
        {
            var list = new List<object>();

            for (var i = 0; i < 40; i++)
            {
                var thread = new Thread(() =>
                {
                    for (var j = 0; j < 10000; j++)
                    {
                        try
                        {
                            list.Add(null);

                        }
                        catch (Exception e)
                        {
                            Console.WriteLine($"{e}\r\n");
                            break;
                        }
                    }
                });

                thread.Start();
            }

            Console.ReadLine();
        }
    }
}