wpf应用程序中的调用目标抛出了异常

Question

我编写了一个简单的wpf应用程序来绑定datagrid中的数据。它在下一行运行时抛出错误。

string ConString = System.Configuration.ConfigurationManager
                         .ConnectionStrings["ConString"].ToString();

异常显示：Exception has been thrown by the target of an invocation."

InnerException:{"Object reference not set to an instance of an object."}

Answer 1

可能System.Configuration.ConfigurationManager.ConnectionStrings [“ConString”]为NULL或 System.Configuration.ConfigurationManager.ConnectionStrings为NULL。