Asp.net 为什么一个含糊不清的控制器尝试错误处理的例外会扰乱管道？

我正在尝试一些错误处理，而这个特定的错误似乎把事情搞砸了

我有一个订阅HttpApplication.Error事件处理程序的HttpModule（见下文），在这里我清除错误并编写一些虚拟响应内容

这对“正常”应用程序错误很好，但是当我得到关于不明确控制器的错误时，它会像往常一样进入处理程序，但是更改的响应被完全忽略，管道中的执行流似乎有一些小故障，对MVC之外的相同资源创建IIS子请求，根据请求的原始路径，导致IIS错误页面，该页面无法列出目录或文件不存在

复制：

创建一个新的模板化MVC项目

添加新区域并创建HomeController（这将与默认HomeController冲突）

运行应用程序时，您应该会看到一个关于不明确控制器的ASP.NET错误页面

添加下面提供的HttpModule

运行应用程序，这将导致DirectoryListingModule出现403.14 IIS错误页面

在新区域中删除或重命名不明确的控制器，但在默认HomeController的索引操作中创建运行时错误（例如DivideByZero）

运行该应用程序，这将产生一个200响应，并如预期的那样显示“helloworld”

public class HttpModule : IHttpModule
{
    public void Init(HttpApplication context)
    {
        context.Error += HandleApplicationError;
    }

    private void HandleApplicationError(object sender, EventArgs e)
    {
        var response = HttpContext.Current.Response;
        var server = ((HttpApplication)sender).Server;
        server.ClearError();
        response.Clear();
        response.Write("Hello world");
    }

    public void Dispose()
    {
    }
}

---

这里发生了什么？当我试图清除错误并更改响应时，当我们得到关于不明确控制器的异常时，为什么会出现问题？

该行为取决于引发请求处理管道异常的位置

• 在控制器不明确的情况下，路由系统会找到与url匹配的路由，并尝试获取将处理请求的IHttpHandler。但是，在尝试获取IHttpHandler时引发异常，请检查此堆栈跟踪：

  at System.Web.Mvc.DefaultControllerFactory.GetControllerTypeWithinNamespaces(RouteBase route, String controllerName, HashSet`1 namespaces)
  at System.Web.Mvc.DefaultControllerFactory.GetControllerType(RequestContext requestContext, String controllerName)
  at System.Web.Mvc.DefaultControllerFactory.System.Web.Mvc.IControllerFactory.GetControllerSessionBehavior(RequestContext requestContext, String controllerName)
  at System.Web.Mvc.MvcRouteHandler.GetSessionStateBehavior(RequestContext requestContext)
  at System.Web.Mvc.MvcRouteHandler.GetHttpHandler(RequestContext requestContext)
  at System.Web.Mvc.MvcRouteHandler.System.Web.Routing.IRouteHandler.GetHttpHandler(RequestContext requestContext)
  at System.Web.Routing.UrlRoutingModule.PostResolveRequestCache(HttpContextBase context)
  at System.Web.Routing.UrlRoutingModule.OnApplicationPostResolveRequestCache(Object s atder, Ev attArgs e)
  at System.Web.HttpApplication.SyncEv attExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
  at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
  

  at WebApplication3.Controllers.HomeController.ThrowError() at g:\Documents\Visual Studio 2012\Projects\WebApplication3\WebApplication3\Controllers\HomeController.cs:line 32
  at lambda_method(Closure , ControllerBase , Object[] )
  at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
  at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
  at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.ActionInvocation.InvokeSynchronousActionMethod()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__36(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3c()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass45.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3e()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass30.<BeginInvokeActionMethodWithFilters>b__2f(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<>c__DisplayClass28.<BeginInvokeAction>b__19()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<BeginInvokeAction>b__1b(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult)
  at System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult)
  at System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult)
  at System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult)
  at System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__4(IAsyncResult asyncResult, ProcessRequestState innerState)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult)
  at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result)
  at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
  at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
  

  由于路由模块无法获取处理程序，IIS将尝试使用其他模块处理它。这意味着它将尝试使用IIS上默认启用的

  DirectoryListingModule

  和

  StaticFileModule

  为请求提供服务

• 当在控制器操作中引发异常时，请求已经分配了一个IHttpHandler，该IHttpHandler正在处理该请求。检查不同的堆栈跟踪：

  at System.Web.Mvc.DefaultControllerFactory.GetControllerTypeWithinNamespaces(RouteBase route, String controllerName, HashSet`1 namespaces)
  at System.Web.Mvc.DefaultControllerFactory.GetControllerType(RequestContext requestContext, String controllerName)
  at System.Web.Mvc.DefaultControllerFactory.System.Web.Mvc.IControllerFactory.GetControllerSessionBehavior(RequestContext requestContext, String controllerName)
  at System.Web.Mvc.MvcRouteHandler.GetSessionStateBehavior(RequestContext requestContext)
  at System.Web.Mvc.MvcRouteHandler.GetHttpHandler(RequestContext requestContext)
  at System.Web.Mvc.MvcRouteHandler.System.Web.Routing.IRouteHandler.GetHttpHandler(RequestContext requestContext)
  at System.Web.Routing.UrlRoutingModule.PostResolveRequestCache(HttpContextBase context)
  at System.Web.Routing.UrlRoutingModule.OnApplicationPostResolveRequestCache(Object s atder, Ev attArgs e)
  at System.Web.HttpApplication.SyncEv attExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
  at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
  

  at WebApplication3.Controllers.HomeController.ThrowError() at g:\Documents\Visual Studio 2012\Projects\WebApplication3\WebApplication3\Controllers\HomeController.cs:line 32
  at lambda_method(Closure , ControllerBase , Object[] )
  at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
  at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
  at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.ActionInvocation.InvokeSynchronousActionMethod()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__36(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3c()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass45.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3e()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass30.<BeginInvokeActionMethodWithFilters>b__2f(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<>c__DisplayClass28.<BeginInvokeAction>b__19()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass1e.<BeginInvokeAction>b__1b(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult)
  at System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult)
  at System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult)
  at System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult)
  at System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__4(IAsyncResult asyncResult, ProcessRequestState innerState)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
  at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag)
  at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult)
  at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result)
  at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
  at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
  

  ---

  谢谢，看起来不错，但有一件事我仍然不明白，那就是如果我们禁用自定义错误处理，“UrlRoutingModule-4.0”会导致默认错误页面，并且它不会尝试DirectoryListingModule或StaticFileModule。如果您描述的行为是由IIS查找处理程序的失败尝试引起的，为什么只有在我尝试清除响应时才会触发此操作？我清除响应是否会导致IIS对刚才发生的事情产生误解？可能是因为当我不清除错误时，IIS会在尝试获取处理程序失败后将错误注册到管道中，并使用此操作在另一个处理程序中生成错误页，独立于获取处理程序的原始失败尝试。因此，当我清除错误时，IIS不会触发错误页面模块并继续搜索…而不调用

  服务器。ClearError

  错误将不断扩展，直到asp最终处理它，生成死亡的黄屏。因此，如果您删除错误处理代码，或注释调用

  ClearError

  的行，您将看到YSODDo，您是否确切地知道此错误是如何升级的？是否都在UrlRoutingModule中处理？我在看跟踪文件，但没什么收获。希望有一种更明确的方式来遵循IIS的流程。我恐怕不知道导致YSOD的asp net内部异常处理过程，但我猜它将是默认asp net请求管道的一部分。如果将

  Application\u Error

  和

  Application\u EndRequest

  方法添加到global.asax，您将看到在错误发生后触发结束请求，并且清除响应并用YSOD替换，因此可能有一个全局模块订阅了OnError事件。（我不熟悉此代码，因此可能是错的）