blocks|key|335074|text|您需要与控制器相对应的操作不带参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|335075|对于您拥有的控制器/操作组合，如下所示：|335076|public+ActionResult+Action(int+parameter)
{

}|code-block|syntax|javascript|335077|但是你需要|335078|public+ActionResult+Action()
{

}|335079|此外，请查看Phil+Haack的Route+Debugger以排除路由故障。|offset|length|335080|entityMap|0|LINK|mutability|MUTABLE|url|http://haacked.com/archive/2008/03/13/url-routing-debugger.aspx^0|0|0|0|0|0|H|E|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|13|8|@]|9|@$O|14|P|15|1|16]]|A|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

You need the action that corresponds to the controller to not have a parameter.

Looks like for the controller / action combination you have:

<pre><code>public ActionResult Action(int parameter)
{

}
</code></pre>

but you need 

<pre><code>public ActionResult Action()
{

}
</code></pre>

Also, check out Phil Haack's <a href="http://haacked.com/archive/2008/03/13/url-routing-debugger.aspx" rel="noreferrer">Route Debugger</a> to troubleshoot routes.

blocks|key|3305632|text|默认情况下，MVC控制器需要不带参数的默认构造函数。最简单的方法是创建一个默认构造函数，它调用带参数的构造函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3305633|public+MyController()+:+this(new+Helper())+{
}

public+MyController(IHelper+helper)+{
++this.helper+=+helper;
}|code-block|syntax|javascript|3305634|但是，您可以通过滚动自己的ControllerFactory来覆盖此功能。这样你就可以告诉MVC，当你创建一个MyController时，给它一个Helper的实例。|offset|length|style|CODE|3305635|这允许你在MVC中使用依赖注入框架，并且真正地将所有东西解耦。StructureMap+website就是一个很好的例子。整个快速入门都很好，他在“自动布线”一文中详细介绍了MVC。|3305636|entityMap|0|LINK|mutability|MUTABLE|url|http://structuremap.sourceforge.net/QuickStart.htm^0|0|0|D|H|1J|C|21|6|0|V|K|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@$I|Z|J|10|K|L]|$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|15|8|@]|9|@$I|16|J|17|1|18]]|A|$]]|$1|O|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

By default, MVC Controllers require a default constructor with no parameters. The simplest would be to make a default constructor that calls the one with parameters: 

<pre><code>public MyController() : this(new Helper()) {
}

public MyController(IHelper helper) {
 this.helper = helper;
}
</code></pre>

However, you can override this functionality by rolling your own <code>ControllerFactory</code>. This way you can tell MVC that when you are creating a <code>MyController</code> give it an instance of <code>Helper</code>.

This allows you to use Dependency Injection frameworks with MVC, and really decouple everything. A good example of this is over at the <a href="http://structuremap.sourceforge.net/QuickStart.htm" rel="noreferrer">StructureMap website</a>. The whole quickstart is good, and he gets specific to MVC towards the bottom at "Auto Wiring".

blocks|key|335099|text|我刚刚遇到了类似的问题。当Model没有无参数构造函数时，也会发生同样的异常。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|335100|调用堆栈正在计算一个负责创建模型的新实例的方法。|335101|335102|+System.Web.Mvc.DefaultModelBinder.CreateModel(ControllerContext+controllerContext，ModelBindingContext+bindingContext，modelType类型)|blockquote|BOLD|335103|335104|335105|335106|下面是一个示例：|335107|public+class+MyController+:+Controller
{
++++public+ActionResult+Action(MyModel+model)
++++{

++++}
}

public+class+MyModel
{
++++public+MyModel(IHelper+helper)+//+MVC+cannot+call+that
++++{
++++++++//+...
++++}

++++public+MyModel()+//+MVC+can+call+that
++++{
++++}
}|code-block|syntax|javascript|335108|entityMap^0|D|5|0|0|0|Z|B|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|12|8|@]|D|@]|E|$]]|$1|I|3|J|5|K|7|13|8|@$9|14|A|15|B|L]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|16|8|@]|D|@]|E|$]]|$1|N|3|-4|5|6|7|17|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|18|8|@]|D|@]|E|$]]|$1|P|3|Q|5|6|7|19|8|@]|D|@]|E|$]]|$1|R|3|S|5|T|7|1A|8|@]|D|@]|E|$U|V]]|$1|W|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|X|$]]

I just had a similar problem. The same exception occurs when a <code>Model</code> has no parameterless constructor.

The call stack was figuring a method responsible for creating a new instance of a model.

<blockquote>
 System.Web.Mvc.DefaultModelBinder.CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
</blockquote>

<hr>

Here is a sample:

<pre><code>public class MyController : Controller
{
 public ActionResult Action(MyModel model)
 {

 }
}

public class MyModel
{
 public MyModel(IHelper helper) // MVC cannot call that
 {
 // ...
 }

 public MyModel() // MVC can call that
 {
 }
}
</code></pre>

blocks|key|330149|text|在以下情况下，我得到了相同的错误：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|330150|使用自定义ModelView，两个操作(GET和POST)都传递包含两个对象的ModelView：|330151|public+ActionResult+Add(int?+categoryID)
{
++++...
++++ProductViewModel+productViewModel+=+new+ProductViewModel(
++++++++++++product,
++++++++++++rootCategories
++++++++++++);
++++return+View(productViewModel);+
}|code-block|syntax|javascript|330152|这篇文章也接受了相同的模型视图：|330153|[HttpPost]
[ValidateInput(false)]
public+ActionResult+Add(ProductModelView+productModelView)
{...}|330154|问题是视图收到了ModelView+(需要产品和类别列表信息)，但是在提交之后只返回了Product对象，但是POST+Add期望返回一个ProductModelView，它传递了一个NULL，但是ProductModelView+only构造函数需要两个参数(+product，RootCategories)，然后它试图为这个NULL情况找到另一个没有参数的构造函数，然后失败并返回"no+parameterle...“|330155|所以，修复POST+Add如下所示来纠正这个问题：|330156|[HttpPost]
[ValidateInput(false)]
public+ActionResult+Add(Product+product)
{...}|330157|希望这篇文章能对某些人有所帮助(我花了大半天的时间才找到答案！)|330158|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|12|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|13|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|14|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

I got the same error when:

Using a custom ModelView, both Actions (GET and POST) were passing the ModelView that contained two objects:

<pre><code>public ActionResult Add(int? categoryID)
{
 ...
 ProductViewModel productViewModel = new ProductViewModel(
 product,
 rootCategories
 );
 return View(productViewModel); 
}
</code></pre>

And the POST also accepting the same model view:

<pre><code>[HttpPost]
[ValidateInput(false)]
public ActionResult Add(ProductModelView productModelView)
{...}
</code></pre>

Problem was the View received the ModelView (needed both product and list of categories info), but after submitted was returning only the Product object, but as the POST Add expected a ProductModelView it passed a NULL but then the ProductModelView only constructor needed two parameters(Product, RootCategories), then it tried to find another constructor with no parameters for this NULL case then fails with "no parameterles..."

So, fixing the POST Add as follows correct the problem:

<pre><code>[HttpPost]
[ValidateInput(false)]
public ActionResult Add(Product product)
{...}
</code></pre>

Hope this can help somebody (I spent almost half day to find this out!).

blocks|key|3305808|text|http://tekpub.com/conferences/mvcconf上的第一个视频|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3305809|47:10分钟内显示错误，并说明如何覆盖默认ControllerFactory。即创建结构图控制器工厂。|3305810|基本上，您可能正在尝试实现依赖注入？？|3305811|问题是接口依赖。|3305812|entityMap|0|LINK|mutability|MUTABLE|url|http://tekpub.com/conferences/mvcconf^0|0|11|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@]|C|$]]|$1|H|3|I|5|6|7|X|8|@]|9|@]|C|$]]|$1|J|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]]]

First video on <a href="http://tekpub.com/conferences/mvcconf" rel="nofollow">http://tekpub.com/conferences/mvcconf</a>

47:10 minutes in show the error and shows how to override the default ControllerFactory.
I.e. to create structure map controller factory.

Basically, you are probably trying to implement dependency injection??

The problem is that is the interface dependency.

blocks|key|332875|text|我也一样。我的问题出现是因为我忘记了我的基本模型类已经具有在视图中定义的名称的属性。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|332876|public+class+CTX+:+DbContext+{++//+context+with+domain+models
++++public+DbSet<Products>+Products+{+get;+set;+}++//+"Products"+is+the+source+property
++++public+CTX()+:+base("Entities")+{}
}

public+class+BaseModel+:+CTX+{+...+}
public+class+ProductModel+:+BaseModel+{+...+}
public+class+OrderIndexModel+:+OrderModel++{+...+}|code-block|syntax|javascript|332877|..。和控制器处理模型：|332878|[HttpPost]
[ValidateInput(false)]
public+ActionResult+Index(OrderIndexModel+order)+{+...+}|332879|没什么特别的，对吧？然后我定义了视图..。|332880|<div+class="dataItem">
++++<%25=Html.Label("Products")%25>
++++<%25=Html.Hidden("Products",+Model.index)%25>+++//+I+FORGOT+THAT+I+ALREADY+HAVE+PROPERTY+CALLED+"Products"
++++<%25=Html.DropDownList("ProductList",+Model.products)%25>
++++<%25=Html.ActionLink("Delete",+"D")%25>
</div>|332881|..。这会在POST请求时导致“无参数构造函数”错误。|332882|希望这能有所帮助。|332883|entityMap^0|K|C|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|14|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|16|8|@]|D|@]|E|$]]|$1|U|3|V|5|6|7|17|8|@]|D|@]|E|$]]|$1|W|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|X|$]]

The same for me.
My problem appeared because i forgot that my base model class already has property with the name which was defined in the view.

<pre><code>public class CTX : DbContext { // context with domain models
 public DbSet&lt;Products&gt; Products { get; set; } // "Products" is the source property
 public CTX() : base("Entities") {}
}

public class BaseModel : CTX { ... }
public class ProductModel : BaseModel { ... }
public class OrderIndexModel : OrderModel { ... }
</code></pre>

... and controller processing model : 

<pre><code>[HttpPost]
[ValidateInput(false)]
public ActionResult Index(OrderIndexModel order) { ... }
</code></pre>

Nothing special, right? But then i define the view ...

<pre><code>&lt;div class="dataItem"&gt;
 &lt;%=Html.Label("Products")%&gt;
 &lt;%=Html.Hidden("Products", Model.index)%&gt; // I FORGOT THAT I ALREADY HAVE PROPERTY CALLED "Products"
 &lt;%=Html.DropDownList("ProductList", Model.products)%&gt;
 &lt;%=Html.ActionLink("Delete", "D")%&gt;
&lt;/div&gt;
</code></pre>

... which causes "Parameterless constructor" error on POST request.

Hope that helps.

blocks|key|335261|text|使用IDependencyResolver时也会发生此错误，例如使用IoC容器时，并且依赖项解析器返回null。在本例中，ASP.NET+MVC3默认使用DefaultControllerActivator来创建对象。如果正在创建的对象没有公共的无参数构造函数，那么只要所提供的依赖关系解析器返回null，就会抛出异常。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|335262|下面就是这样的堆栈跟踪：|335263|[MissingMethodException:+No+parameterless+constructor+defined+for+this+object.]
+++System.RuntimeTypeHandle.CreateInstance(RuntimeType+type,+Boolean+publicOnly,+Boolean+noCheck,+Boolean&+canBeCached,+RuntimeMethodHandleInternal&+ctor,+Boolean&+bNeedSecurityCheck)+%2B0
+++System.RuntimeType.CreateInstanceSlow(Boolean+publicOnly,+Boolean+skipCheckThis,+Boolean+fillCache)+%2B98
+++System.RuntimeType.CreateInstanceDefaultCtor(Boolean+publicOnly,+Boolean+skipVisibilityChecks,+Boolean+skipCheckThis,+Boolean+fillCache)+%2B241
+++System.Activator.CreateInstance(Type+type,+Boolean+nonPublic)+%2B69
+++System.Web.Mvc.DefaultControllerActivator.Create(RequestContext+requestContext,+Type+controllerType)+%2B67

[InvalidOperationException:+An+error+occurred+when+trying+to+create+a+controller+of+type+'My.Namespace.MyController'.+Make+sure+that+the+controller+has+a+parameterless+public+constructor.]
+++System.Web.Mvc.DefaultControllerActivator.Create(RequestContext+requestContext,+Type+controllerType)+%2B182
+++System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext+requestContext,+Type+controllerType)+%2B80
+++System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext+requestContext,+String+controllerName)+%2B74
+++System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase+httpContext,+IController&+controller,+IControllerFactory&+factory)+%2B232
+++System.Web.Mvc.<>c__DisplayClass6.<BeginProcessRequest>b__2()+%2B49
+++System.Web.Mvc.<>c__DisplayClassb`1.<ProcessInApplicationTrust>b__a()+%2B13
+++System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action+f)+%2B7
+++System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action+action)+%2B22
+++System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Func`1+func)+%2B124
+++System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase+httpContext,+AsyncCallback+callback,+Object+state)+%2B98
+++System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext+httpContext,+AsyncCallback+callback,+Object+state)+%2B50
+++System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext+context,+AsyncCallback+cb,+Object+extraData)+%2B16
+++System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()+%2B8963444
+++System.Web.HttpApplication.ExecuteStep(IExecutionStep+step,+Boolean&+completedSynchronously)+%2B184|code-block|syntax|javascript|335264|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.web.mvc.idependencyresolver%2528v=vs.98%2529.aspx^0|2|J|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

This error also occurs when using an <a href="http://msdn.microsoft.com/en-us/library/system.web.mvc.idependencyresolver%28v=vs.98%29.aspx" rel="noreferrer">IDependencyResolver</a>, such as when using an IoC container, and the dependency resolver returns null. In this case ASP.NET MVC 3 defaults to using the DefaultControllerActivator to create the object. If the object being created does not have a public no-args constructor an exception will then be thrown any time the provided dependency resolver has returned null.

Here's one such stack trace:

<pre><code>[MissingMethodException: No parameterless constructor defined for this object.]
 System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean&amp; canBeCached, RuntimeMethodHandleInternal&amp; ctor, Boolean&amp; bNeedSecurityCheck) +0
 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache) +98
 System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean skipCheckThis, Boolean fillCache) +241
 System.Activator.CreateInstance(Type type, Boolean nonPublic) +69
 System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +67

[InvalidOperationException: An error occurred when trying to create a controller of type 'My.Namespace.MyController'. Make sure that the controller has a parameterless public constructor.]
 System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +182
 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +80
 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +74
 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController&amp; controller, IControllerFactory&amp; factory) +232
 System.Web.Mvc.&lt;&gt;c__DisplayClass6.&lt;BeginProcessRequest&gt;b__2() +49
 System.Web.Mvc.&lt;&gt;c__DisplayClassb`1.&lt;ProcessInApplicationTrust&gt;b__a() +13
 System.Web.Mvc.SecurityUtil.&lt;GetCallInAppTrustThunk&gt;b__0(Action f) +7
 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22
 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Func`1 func) +124
 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +98
 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +50
 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +16
 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8963444
 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously) +184
</code></pre>

blocks|key|331710|text|如果您的模型使用SelectList，也会导致这种情况，因为它没有无参数的构造函数|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|331711|public+class+MyViewModel
{
++++public+SelectList+Contacts+{+get;set;+}
}|code-block|syntax|javascript|331712|如果这是原因，你需要重构你的模型，以一种不同的方式完成它。因此，使用IEnumerable<Contact>并编写一个扩展方法来创建具有不同属性定义的下拉列表：|CODE|331713|public+class+MyViewModel
{
++++public+Contact+SelectedContact+{+get;set;+}
++++public+IEnumerable<Contact>+Contacts+{+get;set;+}
}

public+static+MvcHtmlString+DropDownListForContacts(this+HtmlHelper+helper,+IEnumerable<Contact>+contacts,+string+name,+Contact+selectedContact)
{
++++//+Create+a+List<SelectListItem>,+populate+it,+return+DropDownList(..)
}|331714|或者你可以使用@Mark和@krilovich方法，只需要将SelectList替换为IEnumerable，它也可以与MultiSelectList一起工作。|331715|+public+class+MyViewModel
++++{
++++++++public+Contact+SelectedContact+{+get;set;+}
++++++++public+IEnumerable<SelectListItem>+Contacts+{+get;set;+}
++++}|331716|entityMap^0|J|M|0|0|Y|K|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Z|8|@$9|10|A|11|B|M]]|D|@]|E|$]]|$1|N|3|O|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|P|3|Q|5|6|7|13|8|@]|D|@]|E|$]]|$1|R|3|S|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|T|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|U|$]]

This can also be caused if your Model is using a SelectList, as this has no parameterless constructor:

<pre><code>public class MyViewModel
{
 public SelectList Contacts { get;set; }
}
</code></pre>

You'll need to refactor your model to do it a different way if this is the cause. So using an <code>IEnumerable&lt;Contact&gt;</code> and writing an extension method that creates the drop down list with the different property definitions:

<pre><code>public class MyViewModel
{
 public Contact SelectedContact { get;set; }
 public IEnumerable&lt;Contact&gt; Contacts { get;set; }
}

public static MvcHtmlString DropDownListForContacts(this HtmlHelper helper, IEnumerable&lt;Contact&gt; contacts, string name, Contact selectedContact)
{
 // Create a List&lt;SelectListItem&gt;, populate it, return DropDownList(..)
}
</code></pre>

Or you can use the @Mark and @krilovich approach, just need replace SelectList to IEnumerable, it's works with MultiSelectList too.

<pre><code> public class MyViewModel
 {
 public Contact SelectedContact { get;set; }
 public IEnumerable&lt;SelectListItem&gt; Contacts { get;set; }
 }
</code></pre>

blocks|key|332959|text|我也有这个问题，我想我应该分享一下，因为我找不到上面的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|332960|这是我的代码|332961|return+RedirectToAction("Overview",+model.Id);|offset|length|style|CODE|332962|调用此ActionResult：|332963|public+ActionResult+Overview(int+id)|332964|我假设它足够聪明，可以弄清楚我传递给它的值是Overview的id参数，但事实并非如此。这就解决了这个问题：|332965|return+RedirectToAction("Overview",+new+{id+=+model.Id});|332966|entityMap^0|0|0|0|1A|0|0|0|10|0|0|0|1L|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|V|8|@$F|W|G|X|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|Y|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|Z|8|@$F|10|G|11|H|I]]|9|@]|A|$]]|$1|N|3|O|5|6|7|12|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|13|8|@$F|14|G|15|H|I]]|9|@]|A|$]]|$1|R|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|S|$]]

I had this problem as well and thought I'd share since I can't find my problem above.

This was my code

<code>return RedirectToAction("Overview", model.Id);</code>

Calling this ActionResult:

<code>public ActionResult Overview(int id)</code>

I assumed it would be smart enough to figure out that the value I pass it is the id paramter for Overview, but it's not. This fixed it:

<code>return RedirectToAction("Overview", new {id = model.Id});</code>

blocks|key|3305987|text|我遇到了一个类似的问题，基本上要点是，操作方法中有一些参数不是由Model+Binding+process提供的(换句话说，这些字段不是由提交页面提交的)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3305988|即使提供了除一个参数之外的所有参数，即使缺少的参数是可以为空的类型，也会出现此问题。|3305989|该问题也可能是由于输入错误造成的，即参数的名称和表单域的名称不相同。|3305990|解决方案是1)验证名称是否匹配2)为参数提供默认值3)或提供另一个不带此参数的操作方法。|3305991|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

I had a similar problem, and basically the point is that there are some arguments in the action method that were not supplied by the Model Binding process, (and in other words these fields were not submitted by the submitting page).

This problem will come up even if all arguments but one are supplied, and even if the one missing is a nullable type.

The problem might also be a result of a typo, in which the name of the argument and name of the form field will not be identical.

The solution is to 1) verify that the names match up 2) provide a default value for the argument 3) or provide another action method without this argument.

blocks|key|330251|text|我也有同样的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|330252|如果你使用一个接口来解耦你的控制器(比如我)，你可以使用structuremap.mvc+(3或者4-+DbContext包)在你的控制器类中使用一个结构。这将为您提供一个DependencyResolution文件夹。只需将注释行改为For<+InterfaceClass+>()和Use<+DbContextClass+>()即可。|offset|length|style|BOLD|330253|entityMap^0|0|S|G|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

I had the same problem...

If your using a interface to decouple your connection against your DbContext (like me) you can use structuremap.mvc (3 or 4 - nudget package) to be able to use a constructure in your controller class. This will give you a DependencyResolution folder. Just change the commented line with your For&lt; InterfaceClass >() and to Use&lt; DbContextClass >().

blocks|key|330276|text|你可以在MVC框架中的许多不同地方得到这个异常(例如，它不能创建控制器，或者它不能创建一个模型来提供控制器)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|330277|我发现的诊断此问题的唯一简单方法是用您自己的代码覆盖尽可能接近异常的MVC。然后，当此异常发生时，您的代码将在Visual+Studio内中断，并且您可以从堆栈跟踪中读取导致问题的类型。|330278|这似乎是一个可怕的方法来解决这个问题，但它非常快，而且非常一致。|330279|例如，如果此错误发生在MVC+DefaultModelBinder内部(您可以通过检查堆栈跟踪来了解)，则将DefaultModelBinder替换为以下代码：|330280|public+class+MyDefaultModelBinder+:+System.Web.Mvc.DefaultModelBinder
{
++++protected+override+object+CreateModel(System.Web.Mvc.ControllerContext+controllerContext,+System.Web.Mvc.ModelBindingContext+bindingContext,+Type+modelType)
++++{
++++++++return+base.CreateModel(controllerContext,+bindingContext,+modelType);
++++}
}|code-block|syntax|javascript|330281|并更新您的Global.asax.cs：|330282|public+class+MvcApplication+:+System.Web.HttpApplication
{
...
++++protected+void+Application_Start(object+sender,+EventArgs+e)
++++{
++++++++ModelBinders.Binders.DefaultBinder+=+new+MyDefaultModelBinder();
++++}
}|330283|现在，当你下一次得到这个异常时，Visual+Studio将在你的MyDefaultModelBinder类中停止，你可以检查"modelType“属性，看看是什么类型导致了这个问题。|330284|上面的例子只适用于在模型绑定过程中出现“没有为该对象定义无参数构造函数”异常的情况。但是可以为MVC中的其他扩展点编写类似的代码(例如，控制器构造)。|330285|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Y|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|Z|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|10|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|12|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|14|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

You can get this exception at many different places in the MVC framework (e.g. it can't create the controller, or it can't create a model to give that controller).

The only easy way I've found to diagnose this problem is to override MVC as close to the exception as possible with your own code. Then your code will break inside Visual Studio when this exception occurs, and you can read the Type causing the problem from the stack trace.

This seems like a horrible way to approach this problem, but it's very fast, and very consistent.

For example, if this error is occurring inside the MVC DefaultModelBinder (which you will know by checking the stack trace), then replace the DefaultModelBinder with this code:

<pre><code>public class MyDefaultModelBinder : System.Web.Mvc.DefaultModelBinder
{
 protected override object CreateModel(System.Web.Mvc.ControllerContext controllerContext, System.Web.Mvc.ModelBindingContext bindingContext, Type modelType)
 {
 return base.CreateModel(controllerContext, bindingContext, modelType);
 }
}
</code></pre>

And update your Global.asax.cs:

<pre><code>public class MvcApplication : System.Web.HttpApplication
{
...
 protected void Application_Start(object sender, EventArgs e)
 {
 ModelBinders.Binders.DefaultBinder = new MyDefaultModelBinder();
 }
}
</code></pre>

Now the next time you get that exception, Visual Studio will stop inside your MyDefaultModelBinder class, and you can check the "modelType" property to see what type caused the problem.

The example above works for when you get the "No parameterless constructor defined for this object" exception during model binding, only. But similar code can be written for other extension points in MVC (e.g. controller construction).

blocks|key|335386|text|虽然这对一些人来说可能是显而易见的，但对我来说，这个错误的罪魁祸首是我的MVC方法绑定到了一个包含Tuple<>类型属性的模型。Tuple<>没有无参数的构造函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|335387|entityMap^0|1D|7|1S|7|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

While this may be obvious to some, the culprit of this error for me was my MVC method was binding to a model that contained a property of type <code>Tuple&lt;&gt;</code>. <code>Tuple&lt;&gt;</code> has no parameterless constructor.

blocks|key|3093468|text|我得到了同样的错误，在我的例子中，罪魁祸首是构造函数，既不是公共的也不是私有的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3093469|3093470|没有为此对象定义无参数构造函数。|blockquote|3093471|3093472|异常详细信息:+System.MissingMethodException:没有为此对象定义无参数构造函数。|3093473|3093474|Repro代码:确保构造函数前面有public。|3093475|public+class+Chuchi()
{
+++++Chuchi()++++//+The+problem+is+this+line.+Public+is+missing
+++++{
+++++++++//+initialization
+++++++++name="Tom+Hanks";
+++++}

++++public+string+name
++++{
++++++++get;
++++++++set;
++++}
}|code-block|syntax|javascript|3093476|entityMap^0|R|C|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]|$1|G|3|H|5|I|7|10|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|11|8|@]|D|@]|E|$]]|$1|K|3|L|5|6|7|12|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|13|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|14|8|@]|D|@]|E|$]]|$1|P|3|Q|5|R|7|15|8|@]|D|@]|E|$S|T]]|$1|U|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|V|$]]

I got the same error, the culprit in my case was the constructor which was neither public nor private.

<blockquote>
 No parameterless constructor defined for this object.
 
 Exception Details: System.MissingMethodException: No parameterless constructor defined for this object.
</blockquote>

Repro code: Make sure the constructor has public before it.

<pre><code>public class Chuchi()
{
 Chuchi() // The problem is this line. Public is missing
 {
 // initialization
 name="Tom Hanks";
 }

 public string name
 {
 get;
 set;
 }
}
</code></pre>

blocks|key|3093478|text|由于没有无参数的公共构造器，我得到了相同的异常|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3093479|代码是这样的：|3093480|public+class+HomeController+:+Controller
{++++++++
++++private+HomeController()
++++{
++++++++_repo+=+new+Repository();
++++}|code-block|syntax|javascript|3093481|已更改为|offset|length|style|BOLD|3093482|+public+class+HomeController+:+Controller
{++++++++
++++public+HomeController()
++++{
++++++++_repo+=+new+Repository();
++++}|3093483|问题解决给我了。|3093484|entityMap^0|0|0|0|0|4|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@$K|Y|L|Z|M|N]]|9|@]|A|$]]|$1|O|3|P|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

I got same exception due to there was no parameterless public contructor

Code was like this:

<pre><code>public class HomeController : Controller
{ 
 private HomeController()
 {
 _repo = new Repository();
 }
</code></pre>

changed to 

<pre><code> public class HomeController : Controller
{ 
 public HomeController()
 {
 _repo = new Repository();
 }
</code></pre>

problem resolved to me.

blocks|key|333102|text|当我添加一个新的方法来实例化一个类时，这个错误就开始了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|333103|示例：|333104|++++public+class+myClass
++++{
+++++++++public+string+id{+get;+set;+}
+++++++++public+List<string>+myList{get;+set;}

+++++++++//+error+happened+after+I+added+this
+++++++++public+myClass(string+id,+List<string>+lst)
+++++++++{
+++++++++++++this.id=+id;
+++++++++++++this.myList=+lst;
+++++++++}
+++++}|code-block|syntax|javascript|333105|当我添加了这个更改，添加了一个无参数的构造函数时，错误就解决了。我相信编译器在默认情况下会创建一个无参数的构造器，但是如果你添加了自己的构造器，那么你必须显式地创建它。|333106|++++public+class+myClass
++++{
+++++++++public+string+id{+get;+set;+}
+++++++++public+List<string>+myList{get;+set;}

+++++++++//+error+doesn't+happen+when+I+add+this
+++++++++public+myClass()+{+}

+++++++++//+error+happened+after+I+added+this,+but+no+longer+happens+after+adding+above
+++++++++public+myClass(string+id,+List<string>+lst)
+++++++++{
+++++++++++++this.id=+id;
+++++++++++++this.myList=+lst;
+++++++++}
+++++}|333107|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

This error started for me when I added a new way to instantiate a class. 

Example:

<pre><code> public class myClass
 {
 public string id{ get; set; }
 public List&lt;string&gt; myList{get; set;}

 // error happened after I added this
 public myClass(string id, List&lt;string&gt; lst)
 {
 this.id= id;
 this.myList= lst;
 }
 }
</code></pre>

The error was resolved when I added when I made this change, adding a parameterless constructor. I believe the compiler creates a parameterless constuctor by default but if you add your own then you must explicitly create it.

<pre><code> public class myClass
 {
 public string id{ get; set; }
 public List&lt;string&gt; myList{get; set;}

 // error doesn't happen when I add this
 public myClass() { }

 // error happened after I added this, but no longer happens after adding above
 public myClass(string id, List&lt;string&gt; lst)
 {
 this.id= id;
 this.myList= lst;
 }
 }
</code></pre>

blocks|key|330368|text|我已经在我的表单中添加了一个DropDownList，但是在我的例子中，它并没有(也不打算)与表单一起提交，因为它在<form></form>标记之外：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|330369|@Html.DropDownList("myField",+Model.MyField)|code-block|syntax|javascript|330370|由于模型包含仅供显示的字段，这也导致了No+parameterless+constructor+defined+for+this+object错误，因为根本没有提交字段。|330371|在这种情况下，我通过添加一个排除绑定来修复它：|330372|public+ActionResult+Foo(int+id,+int?+page,+[Bind(Exclude+=+"MyField")]MyModel+model)|330373|entityMap^0|E|C|1M|D|0|0|J|1G|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|11|8|@]|D|@]|E|$]]|$1|O|3|P|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

I'd added a <code>DropDownList</code> to my form, however in my case it wasn't (and wasn't intended to be) submitted with the form as it was outside of the <code>&lt;form&gt;&lt;/form&gt;</code> tags:

<pre><code>@Html.DropDownList("myField", Model.MyField)
</code></pre>

As the Model contained the field for display only, this also caused the <code>No parameterless constructor defined for this object</code> error because the field wasn't submitted at all.

In this case I fixed it by adding an exclude binding:

<pre><code>public ActionResult Foo(int id, int? page, [Bind(Exclude = "MyField")]MyModel model)
</code></pre>

blocks|key|3093701|text|这发生在我身上，这个页面上的结果是一个很好的资源，引导我走向了许多方向，但我想添加另一种可能性：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3093702|正如在其他回复中所述，创建带参数的构造函数会删除隐式的无参数构造函数，因此您必须显式地键入它。|3093703|我的问题是，一个带有默认参数的构造函数也触发了这个异常。|3093704|给出错误：|3093705|public+CustomerWrapper(CustomerDto+customer+=+null){...}|code-block|syntax|javascript|3093706|作品：|3093707|public+CustomerWrapper(CustomerDto+customer){...}
public+CustomerWrapper():this(null){}|3093708|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|W|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|Y|8|@]|9|@]|A|$K|L]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

This happened to me, and the results on this page were a good resource that led me in many directions, but I would like to add another possibility:

As stated in other replies, creating a constructor with parameters removes the implicit parameterless constructor, so you have to explicitly type it.

What was my problem was that a constructor with default parameters also triggered this exception.

Gives errors:

<pre><code>public CustomerWrapper(CustomerDto customer = null){...}
</code></pre>

Works:

<pre><code>public CustomerWrapper(CustomerDto customer){...}
public CustomerWrapper():this(null){}
</code></pre>

blocks|key|331906|text|因此，在进行ajax调用时，我以前也收到过这样的消息。所以它基本上要求的是模型类中的一个构造器，它被contoller调用，没有任何参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|331907|下面是一个例子|331908|public+class+MyClass{

+++++public+MyClass(){}+//+so+here+would+be+your+parameterless+constructor

+}|code-block|syntax|javascript|331909|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

So I have gotten that message before as well, when doing an ajax call. So what it's basically asking for is a constructor in that model class that is being called by the contoller, doesn't have any parameter.

Here is an example 

<pre><code>public class MyClass{

 public MyClass(){} // so here would be your parameterless constructor

 }
</code></pre>

blocks|key|330429|text|最有可能的是，您的控制器中可能有参数化的构造函数，而您使用的任何依赖项解析器都不能正确解析依赖项。您需要将断点放在编写依赖关系解析器方法的位置，并且您将在内部异常中得到确切的错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|330430|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Most probably you might have parameterized constructor in your controller and whatever dependency resolver you are using is not able to resolve the dependency properly. You need to put break-point where the dependency resolver method is written and you will get the exact error in inner exception.

blocks|key|330446|text|所有的答案都是创建一个无参数的构造器，如果你不想让任何其他开发人员使用它，而只想使用模型绑定器，那么这并不理想。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|330447|如果另一个开发人员试图使用公共构造函数上面的属性[Obsolete("For+model+binding+only",+true)]，它将抛出一个编译器错误。我花了很长时间才找到这个，希望它能帮到什么人。|offset|length|style|CODE|330448|entityMap^0|0|O|16|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

All of the answers say to create a parameters less constructor which isn't ideal if you don't want any other devs using it and only the model binder.

The attribute <code>[Obsolete("For model binding only", true)]</code> above a public constructor will throw a compiler error if another dev tries to use this. Took me ages to find this, hope it helps someone.

blocks|key|3306525|text|我得到了这个错误。我在我的构造函数中使用接口，而我的依赖解析器无法解析，当我注册它时，错误就消失了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3306526|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I got this error. I was using interfaces in my constructor and my dependency resolver wasn't able to resolve, when i registered it then the error went away.

blocks|key|3093890|text|我也有同样的问题，但后来发现添加任何新的接口和相应的类都需要在Initializable+Module下注册才能进行依赖注入。在我的例子中，它是内部代码，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3093891|[InitializableModule]
[ModuleDependency(typeof(EPiServer.Web.InitializationModule))]
public+class+DependencyResolverInitialization+:+IConfigurableModule
{

++++public+void+ConfigureContainer(ServiceConfigurationContext+context)
++++{
++++++++context.Container.Configure(ConfigureContainer);
++++++++var+structureMapDependencyResolver+=+new+StructureMapDependencyResolver(context.Container);
++++++++DependencyResolver.SetResolver(structureMapDependencyResolver);
++++++++GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerActivator),+structureMapDependencyResolver);
++++}

++++private+void+ConfigureContainer(ConfigurationExpression+container)
++++{
++++++++container.For<IAppSettingService>().Use<AppSettingService>();
++++++++container.For<ISiteSettingService>().Use<SiteSettingService>();
++++++++container.For<IBreadcrumbBuilder>().Use<BreadcrumbBuilder>();
++++++++container.For<IFilterContentService>().Use<FilterContentService>().Singleton();
++++++++container.For<IDependecyFactoryResolver>().Use<DependecyFactoryResolver>();
++++++++container.For<IUserService>().Use<UserService>();
++++++++container.For<IGalleryVmFactory>().Use<GalleryVmFactory>();
++++++++container.For<ILanguageService>().Use<LanguageService>();
++++++++container.For<ILanguageBranchRepository>().Use<LanguageBranchRepository>();
++++++++container.For<ICacheService>().Use<CacheService>();+
++++++++container.For<ISearchService>().Use<SearchService>();
++++++++container.For<IReflectionService>().Use<ReflectionService>();
++++++++container.For<ILocalizationService>().Use<LocalizationService>();
++++++++container.For<IBookingFormService>().Use<BookingFormService>();
++++++++container.For<IGeoService>().Use<GeoService>();
++++++++container.For<ILocationService>().Use<LocationService>();
++++++++RegisterEnterpriseAPIClient(container);
++++}

+++public+void+Initialize(InitializationEngine+context)
++++{
++++}

++++public+void+Uninitialize(InitializationEngine+context)
++++{
++++}

++++public+void+Preload(string[]+parameters)
++++{
++++}
}|code-block|syntax|javascript|3093892|}|3093893|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I had same problem but later found adding any new interface and corresponding class requires it to be registered under Initializable Module for dependency injection. In my case it was inside code as follows:

<pre><code>[InitializableModule]
[ModuleDependency(typeof(EPiServer.Web.InitializationModule))]
public class DependencyResolverInitialization : IConfigurableModule
{

 public void ConfigureContainer(ServiceConfigurationContext context)
 {
 context.Container.Configure(ConfigureContainer);
 var structureMapDependencyResolver = new StructureMapDependencyResolver(context.Container);
 DependencyResolver.SetResolver(structureMapDependencyResolver);
 GlobalConfiguration.Configuration.Services.Replace(typeof(IHttpControllerActivator), structureMapDependencyResolver);
 }

 private void ConfigureContainer(ConfigurationExpression container)
 {
 container.For&lt;IAppSettingService&gt;().Use&lt;AppSettingService&gt;();
 container.For&lt;ISiteSettingService&gt;().Use&lt;SiteSettingService&gt;();
 container.For&lt;IBreadcrumbBuilder&gt;().Use&lt;BreadcrumbBuilder&gt;();
 container.For&lt;IFilterContentService&gt;().Use&lt;FilterContentService&gt;().Singleton();
 container.For&lt;IDependecyFactoryResolver&gt;().Use&lt;DependecyFactoryResolver&gt;();
 container.For&lt;IUserService&gt;().Use&lt;UserService&gt;();
 container.For&lt;IGalleryVmFactory&gt;().Use&lt;GalleryVmFactory&gt;();
 container.For&lt;ILanguageService&gt;().Use&lt;LanguageService&gt;();
 container.For&lt;ILanguageBranchRepository&gt;().Use&lt;LanguageBranchRepository&gt;();
 container.For&lt;ICacheService&gt;().Use&lt;CacheService&gt;(); 
 container.For&lt;ISearchService&gt;().Use&lt;SearchService&gt;();
 container.For&lt;IReflectionService&gt;().Use&lt;ReflectionService&gt;();
 container.For&lt;ILocalizationService&gt;().Use&lt;LocalizationService&gt;();
 container.For&lt;IBookingFormService&gt;().Use&lt;BookingFormService&gt;();
 container.For&lt;IGeoService&gt;().Use&lt;GeoService&gt;();
 container.For&lt;ILocationService&gt;().Use&lt;LocationService&gt;();
 RegisterEnterpriseAPIClient(container);
 }

 public void Initialize(InitializationEngine context)
 {
 }

 public void Uninitialize(InitializationEngine context)
 {
 }

 public void Preload(string[] parameters)
 {
 }
}
</code></pre>

}

blocks|key|335601|text|我也有同样的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|335602|刚从Post+Action方法参数中删除了HttpFileCollectionBase+files，并在方法体中添加了like+HttpFileCollectionBase+files+=+Request.Files;。|offset|length|style|CODE|335603|entityMap^0|0|L|S|1S|19|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]|$D|N|E|O|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|I|$]]

I had the same problem.

Just Removed <code>HttpFileCollectionBase files</code> from Post Action method argument 
and added like <code>HttpFileCollectionBase files = Request.Files;</code> in method body.

blocks|key|3306617|text|在我的例子中，我的类有[Serializable]属性。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3306618|如果您的类为[Serializable]，则需要有一个不带参数的构造函数|3306619|entityMap^0|B|E|0|6|E|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

In my case, my class had the <code>[Serializable]</code> attribute. 

You are required to have a constructor that takes no parameters if your class is <code>[Serializable]</code>

blocks|key|3306634|text|我在域文件夹内的模型中添加了一个无参数的构造函数，问题就解决了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3306635|​|3306636|📷|atomic|offset|length|3306637|3306638|+public+User()
++++++++{

++++++++}|code-block|syntax|javascript|3306639|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/6ca85c95d6123c5aadffec6ac503e513.png|imageAlt^0|0|0|0|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@$G|10|H|11|1|12]]|A|$]]|$1|I|3|C|5|6|7|13|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|14|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V|W|-4]]]]

I added a parameterless constructor to the model inside of DOMAIN Folder, and the problem is solved.
<img src="https://i.stack.imgur.com/Kf7H3.png" alt="enter image description here" />

<pre><code> public User()
 {

 }
</code></pre>

blocks|key|3093978|text|由于缺少依赖项注入器/解析器容器和/或缺少绑定，可能会出现此类型错误|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3093979|3093980|使用NugetPacketManager将依赖项注入器添加到项目中|ordered-list-item|3093981|为类的接口和具体实现添加绑定|3093982|3093983|UnityMConfig.cs|3093984|using+System;
using+Unity;
using+<your_namespace+for+the+interfaces+and+concrete+classes>

namespace+<your_namespace>
{
++++public+static+class+UnityConfig
++++{
++++++++private+static+Lazy<IUnityContainer>+container+=
++++++++++++new+Lazy<IUnityContainer>(()+=>
++++++++++++{
++++++++++++++++var+container+=+new+UnityContainer();
++++++++++++++++RegisterTypes(container);
++++++++++++++++return+container;
++++++++++++});

++++++++public+static+IUnityContainer+Container+=>+container.Value;

++++++++public+static+void+RegisterTypes(IUnityContainer+container)
++++++++{
++++++++++++container.RegisterType+<IInterfaceClassName,+ConcreteImplementationOfInterface>+();
++++++++}
++++}
}|code-block|syntax|javascript|3093985|UnityMvcActivator.cs|3093986|using+System.Linq;
using+System.Web.Mvc;
using+Unity.AspNet.Mvc;

[assembly:+WebActivatorEx.PreApplicationStartMethod(typeof(xxxx.UnityMvcActivator),+nameof(xxxx.UnityMvcActivator.Start))]
[assembly:+WebActivatorEx.ApplicationShutdownMethod(typeof(xxxx.UnityMvcActivator),+nameof(xxxx.UnityMvcActivator.Shutdown))]

namespace+<your_namespace>
{
++++public+static+class+UnityMvcActivator
++++{
++++++++public+static+void+Start()
++++++++{
++++++++++++FilterProviders.Providers.Remove(FilterProviders.Providers.OfType<FilterAttributeFilterProvider>().First());
++++++++++++FilterProviders.Providers.Add(new+UnityFilterAttributeFilterProvider(UnityConfig.Container));
++++++++++++DependencyResolver.SetResolver(new+UnityDependencyResolver(UnityConfig.Container));
++++++++}
++++++++public+static+void+Shutdown()
++++++++{
++++++++++++UnityConfig.Container.Dispose();
++++++++}
++++}
}|3093987|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|W|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|X|8|@]|9|@]|A|$]]|$1|F|3|G|5|E|7|Y|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|10|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|11|8|@]|9|@]|A|$N|O]]|$1|P|3|Q|5|6|7|12|8|@]|9|@]|A|$]]|$1|R|3|S|5|M|7|13|8|@]|9|@]|A|$N|O]]|$1|T|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|U|$]]

This type error may come up due to missing dependency injector/resolver container and/or missing the bindings
<ol>
<li>Add Dependency injector to your project using NugetPacketManager (Unity, Ninject or whichever you like)</li>
<li>Add binding(s) for interface and concrete implementation for the classes</li>
</ol>
UnityMConfig.cs
<pre class="lang-cs prettyprint-override"><code>using System;
using Unity;
using &lt;your_namespace for the interfaces and concrete classes&gt;

namespace &lt;your_namespace&gt;
{
 public static class UnityConfig
 {
 private static Lazy&lt;IUnityContainer&gt; container =
 new Lazy&lt;IUnityContainer&gt;(() =&gt;
 {
 var container = new UnityContainer();
 RegisterTypes(container);
 return container;
 });

 public static IUnityContainer Container =&gt; container.Value;

 public static void RegisterTypes(IUnityContainer container)
 {
 container.RegisterType &lt;IInterfaceClassName, ConcreteImplementationOfInterface&gt; ();
 }
 }
}
</code></pre>
UnityMvcActivator.cs
<pre class="lang-cs prettyprint-override"><code>using System.Linq;
using System.Web.Mvc;
using Unity.AspNet.Mvc;

[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(xxxx.UnityMvcActivator), nameof(xxxx.UnityMvcActivator.Start))]
[assembly: WebActivatorEx.ApplicationShutdownMethod(typeof(xxxx.UnityMvcActivator), nameof(xxxx.UnityMvcActivator.Shutdown))]

namespace &lt;your_namespace&gt;
{
 public static class UnityMvcActivator
 {
 public static void Start()
 {
 FilterProviders.Providers.Remove(FilterProviders.Providers.OfType&lt;FilterAttributeFilterProvider&gt;().First());
 FilterProviders.Providers.Add(new UnityFilterAttributeFilterProvider(UnityConfig.Container));
 DependencyResolver.SetResolver(new UnityDependencyResolver(UnityConfig.Container));
 }
 public static void Shutdown()
 {
 UnityConfig.Container.Dispose();
 }
 }
}
</code></pre>

<pre><code>Server Error in '/' Application.
--------------------------------------------------------------------------------

No parameterless constructor defined for this object. 
Description: 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. 

Exception Details: System.MissingMethodException: No parameterless constructor defined for this object.

Source Error: 


Line 16: HttpContext.Current.RewritePath(Request.ApplicationPath, false);
Line 17: IHttpHandler httpHandler = new MvcHttpHandler();
Line 18: httpHandler.ProcessRequest(HttpContext.Current);
Line 19: HttpContext.Current.RewritePath(originalPath, false);
Line 20: }
</code></pre>

I was following Steven Sanderson's '<a href="http://www.apress.com/book/view/1430210079" rel="noreferrer">Pro ASP.NET MVC Framework</a>' book. On page 132, in accordance with the author's recommendation, I downloaded the ASP.NET MVC Futures assembly, and added it to my MVC project. [Note: This could be a red herring.]

After this, I could no longer load my project. The above error stopped me cold.

My question is not, "Could you help me fix my code?"

Instead, I'd like to know more generally:

<ul>
<li>How should I troubleshoot this issue?</li>
<li>What should I be looking for? </li>
<li>What might the root cause be?</li>
</ul>

It seems like I should understand routing and controllers at a deeper level than I do now.

ASP.NET MVC: No parameterless constructor defined for this object

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Server Error in '/' Application.--------------------------------------------------------------------------------No parameterless constructor defined for this ob...

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