问错误处理asp.net MVC5不允许在事件查看器上查看堆栈跟踪

EN

 <httpErrors errorMode="Custom" existingResponse="Replace"> --><!--defaultPath="/Errors/NotFound"--><!--
  <remove statusCode="404" subStatusCode="-1"/>
  <remove statusCode="500" subStatusCode="-1"/>
  <error statusCode="404" path="/Errors/NotFound" responseMode="ExecuteURL"/>
  <error statusCode="500" path="/Errors/ServerError" responseMode="ExecuteURL"/>
</httpErrors> 

     protected void Application_Error(object sender, EventArgs e)
    {
        var exception = Server.GetLastError();

        var httpStatusCode = (int)HttpStatusCode.InternalServerError;
        try
        {
            httpStatusCode = ((HttpException) exception).GetHttpCode();
        }
        catch (Exception)
        {
        }

        var dateTime = DateTime.Now.ToString();
        var ip = Request.ServerVariables["REMOTE_ADDR"];

        var userName = string.Empty;
        try
        {
            userName = HttpContext.Current.User.Identity.Name;
        }
        catch
        {
        }

       var url = string.Empty;
        if (HttpContext.Current != null)
        {
             url = HttpContext.Current.Request.Url.ToString();
        }


        var log = string.Format("Url: {0} , httpStatusCode: {1}, " +
                                "dateTime: {2}, exceptionMessage: {3}, " +
                                "ipAddress: {4}, userName: {5} ",
            url, httpStatusCode, dateTime, exception.Message, ip, userName);

        ServerAnalytics.CurrentRequest.LogEvent(log);

    }