c#-解决错误-“返回404时,已经添加了具有相同键的项目”

我有如下定义的自定义错误页面处理程序：

if (env.IsDevelopment()){    app.UseDeveloperExceptionPage();    app.UseBrowserLink();}else{    app.UseExceptionHandler("/Error");}app.UseStatusCodePagesWithReExecute("/Error/{0}");app.UseMvc(routes =>{    ...}

然后在错误控制器中：

public class ErrorController : Controller{    public IActionResult Index(int errorCode)    {        switch (errorCode)        {            case 404:                return View($"~/Views/Error/{errorCode}.cshtml");        }        return View(errorCode);    }}

在生产模式下,一切正常,但是在开发中,有两种情况：

>我点击“就像那样”的404页面,并显示我的自定义404页面(正确)
>我强迫404采取行动,例如

if(nothingFound){    return NotFound();}

然后进入ErrorController动作,甚至进入视图(404.cshtml),但之后将显示标题为：

ArgumentException: An item with the same key has already been added.
Key: System.Object

使用app.UseDeveloperExceptionPage()时是否正常,还是配置有误？

更新

堆栈跟踪：

System.ArgumentException: An item with the same key has already been added. Key: System.Object   at System.ThrowHelper.ThrowAddingDuplicateWithKeyArgumentException(Object key)   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeNextResourceFilter>d__22.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ResourceExecutedContext context)   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeAsync>d__20.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)   at Microsoft.AspNetCore.Builder.StatusCodePagesExtensions.<>c__DisplayClass6_0.<<UseStatusCodePagesWithReExecute>b__0>d.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.<Invoke>d__3.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)   at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.<Invoke>d__4.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)   at Microsoft.VisualStudio.Web.BrowserLink.Runtime.BrowserLinkMiddleware.<ExecuteWithFilter>d__7.MoveNext()--- End of stack trace from previous location where exception was thrown ---   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.<Invoke>d__7.MoveNext()

解决方法:

该错误是由于调用UseBrowserLink()引起的,您可以从相关菜单中管理此功能.

如果取消选中“启用浏览器链接”,则错误消失.

我不知道是什么原因引起的,但是这里是指向UseBrowserLink docs的链接

来源：https://www.icode9.com/content-1-522701.html