難以理解堆棧軌跡

Question

我很難重新生成場景或讀取我今天在日誌中得到的下面的錯誤..通常堆棧跟蹤將指向文件和行號等，但作爲你可以看到它下面只是說nullreference例外沒有給我具體的位置。我希望如果你能幫助我讀入到此並找出exaclty正在發生的事情..

System.Web.HttpException (0x80004005): Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerWrapper'. ---> System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object. 
    at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer) 
    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
    at System.Web.UI.Page.HandleError(Exception e) 
    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
    at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
    at System.Web.UI.Page.ProcessRequest() 
    at System.Web.UI.Page.ProcessRequest(HttpContext context) 
    at System.Web.Mvc.ViewPage.ProcessRequest(HttpContext context) 
    at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.<>c__DisplayClass4.<Wrap>b__3() 
    at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func`1 func) 
    at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) 
    at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) 
    at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage) 
    at System.Web.HttpServerUtilityWrapper.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm) 
    at System.Web.Mvc.ViewPage.RenderView(ViewContext viewContext) 
    at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) 
    at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass14.<InvokeActionResultWithFilters>b__11() 
    at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) 
    at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) 
    at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) 
    at System.Web.Mvc.Controller.ExecuteCore() 
    at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.<BeginProcessRequest>b__4() 
    at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() 
    at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() 
    at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) 
System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object. 
    at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) 
    at System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer) 
    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
    at System.Web.UI.Page.HandleError(Exception e) 
    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
    at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
    at System.Web.UI.Page.ProcessRequest() 
    at System.Web.UI.Page.ProcessRequest(HttpContext context) 
    at System.Web.Mvc.ViewPage.ProcessRequest(HttpContext context) 
    at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.<>c__DisplayClass4.<Wrap>b__3() 
    at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func`1 func) 
    at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) 

Answer 1

呀，空引用異常可以有點棘手。它看起來像是在「預訂結帳」視圖內發生的。

Answer 2

堆棧跟蹤的第一行來自最深處（發生錯誤的位置）和下面的行，因爲它會將堆棧備份起來。

我刪除了System。*條目（它浸入到.NET Framework中），剩下的部分是您的頁面和類。它使更多的可讀性，也許更易於管理...

System.Web.HttpException (0x80004005): Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerWrapper'. ---> System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object. 
    at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer) 
    at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer) 
    at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer) 

System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object. 
    at ASP.views_reservation_checkout_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer) 
    at ASP.content_kismetvacation_views_shared_site_master.__RenderBodyContent(HtmlTextWriter __w, Control parameterContainer) 
    at ASP.content_kismetvacation_views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer) 

我看到你的內容頁面有：* views_reservation_checkout_aspx *
和一個視圖：* content_kismetvacation_views_shared_site_master *

最深點顯示網頁名爲ASP.views_reservation_checkout_aspx（ASP/views/reservation/checkout.aspx？），因此您應該將調試工作集中在那裏的對象和控件上。

事情在頁面嘗試：

• 在Visual Studio中設置斷點
  • 和逐步執行代碼行由行，
  • 沿途檢查的事情實例爲null。
  • 查找空的實例的成員調用（例如方法或屬性）。
• 修復和重複