Question

任何人都可以解释这个例外吗？

Object reference not set to an instance of an object.

描述：

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.

异常详细信息：

System.NullReferenceException: Object reference not set to an instance of an object.

来源错误：

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.

堆栈追踪：

[NullReferenceException: Object reference not set to an instance of an object.]
   System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace) +24
   System.Xml.XmlDocument.Load(XmlReader reader) +108
   System.Web.UI.WebControls.XmlDataSource.PopulateXmlDocument(XmlDocument document, CacheDependency& dataCacheDependency, CacheDependency& transformCacheDependency) +342
   System.Web.UI.WebControls.XmlDataSource.GetXmlDocument() +253
   System.Web.UI.WebControls.XmlHierarchicalDataSourceView.Select() +51
   System.Web.UI.WebControls.Menu.DataBindItem(MenuItem item) +326
   System.Web.UI.WebControls.Menu.PerformDataBinding() +99
   System.Web.UI.WebControls.HierarchicalDataBoundControl.PerformSelect() +126
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +125
   System.Web.UI.WebControls.Menu.DataBind() +29
   System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound() +104
   System.Web.UI.WebControls.Menu.EnsureDataBound() +70
   System.Web.UI.WebControls.BaseDataBoundControl.OnPreRender(EventArgs e) +43
   System.Web.UI.WebControls.Menu.OnPreRender(EventArgs e, Boolean registerScript) +89
   System.Web.UI.WebControls.Menu.OnPreRender(EventArgs e) +63
   System.Web.UI.Control.PreRenderRecursiveInternal() +200
   System.Web.UI.Control.PreRenderRecursiveInternal() +322
   System.Web.UI.Control.PreRenderRecursiveInternal() +322
   System.Web.UI.Control.PreRenderRecursiveInternal() +322
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4837

Answer 1

没有看到你的代码就很难说，但是通过堆栈跟踪的外观，我会猜测并说你有一个绑定到XmlDataSource的TreeView / Menu。

显然在数据绑定过程中出现了问题，但是再次看不到填充XmlDataSource的代码，它几乎无法帮助你进一步帮助你。

Answer 2

从XmlReader传递到XmlDocument.Load的{{1}}实例为空，这意味着XmlLoader.Load将空读取器传递给XmlDataSource.PopulateXmlDocument，这发生在XmlDocument.Load 1}}返回null。

发生这种情况的唯一代码路径要求XmlDataSource.GetReader为空或空且 XmlDataSource.DataFile为空，空或仅为空白字符的成本。

null引用异常堆栈

2 个答案: