title: Activation error occurred while trying to get instance of type AccountController, key \"\""
body: <p>That's my <code>AccountController</code>:</p>
  
  <pre><code>[Authorize]
  public class AccountController : Controller
  {
      private UserManager&lt;User&gt; _userManager { get; set; }
  
      public AccountController() : this(new UserManager&lt;User&gt;(new UserStore())) {}
  
      public AccountController(UserManager&lt;User&gt; userManager) {
          _userManager = userManager;
      }
  }
  </code></pre>
  
  <p>And stack trace:</p>
  
  <pre><code>Microsoft.Practices.ServiceLocation.ActivationException was unhandled by user code
    HResult=-2146233088
    Message=Activation error occurred while trying to get instance of type AccountController, key ""
    Source=Microsoft.Practices.ServiceLocation
    StackTrace:
         at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) in c:\Projects\CommonServiceLocator\main\Microsoft.Practices.ServiceLocation\ServiceLocatorImplBase.cs:line 53
         at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType) in c:\Projects\CommonServiceLocator\main\Microsoft.Practices.ServiceLocation\ServiceLocatorImplBase.cs:line 34
         at System.Web.Mvc.DependencyResolver.DelegateBasedDependencyResolver.GetService(Type type)
    InnerException: StructureMap.StructureMapException
         HResult=-2146232832
         Message=StructureMap Exception Code:  202
  No Default Instance defined for PluginFamily Microsoft.AspNet.Identity.IUserStore`1[[Fables.BLL.Entities.User, Fables.BLL, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], Microsoft.AspNet.Identity.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
         Source=StructureMap
         ErrorCode=202
         StackTrace:
              at StructureMap.BuildSession.&lt;.ctor&gt;b__0(Type t) in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 33
              at StructureMap.Util.Cache`2.get_Item(KEY key) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Util\Cache.cs:line 83
              at StructureMap.BuildSession.CreateInstance(Type pluginType) in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 215
              at StructureMap.Pipeline.DefaultInstance.build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\DefaultInstance.cs:line 22
              at StructureMap.Pipeline.Instance.createRawObject(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 103
              at StructureMap.Pipeline.Instance.Build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 69
              at StructureMap.Pipeline.ConstructorInstance.Get(String propertyName, Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 74
              at StructureMap.Pipeline.ConstructorInstance.Get[T](String propertyName, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 79
              at StructureMap.Pipeline.Arguments.Get[T](String propertyName) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Arguments.cs:line 18
              at lambda_method(Closure , IArguments )
              at StructureMap.Construction.BuilderCompiler.FuncCompiler`1.&lt;&gt;c__DisplayClass2.&lt;CreateBuilder&gt;b__0(IArguments args) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Construction\BuilderCompiler.cs:line 56
              at StructureMap.Construction.InstanceBuilder.BuildInstance(IArguments args) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Construction\InstanceBuilder.cs:line 34
              at StructureMap.Pipeline.ConstructorInstance.Build(Type pluginType, BuildSession session, IInstanceBuilder builder) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 237
              at StructureMap.Pipeline.ConstructorInstance.build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 218
              at StructureMap.Pipeline.Instance.createRawObject(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 103
              at StructureMap.Pipeline.Instance.Build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 69
              at StructureMap.Pipeline.ObjectBuilder.ConstructNew(Type pluginType, Instance instance, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ObjectBuilder.cs:line 39
              at StructureMap.Pipeline.ObjectBuilder.Resolve(Type pluginType, Instance instance, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ObjectBuilder.cs:line 27
              at StructureMap.BuildSession.CreateInstance(Type pluginType, Instance instance) in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 176
              at StructureMap.BuildSession.&lt;&gt;c__DisplayClass3.&lt;.ctor&gt;b__1() in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 36
              at StructureMap.BuildSession.CreateInstance(Type pluginType) in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 215
              at StructureMap.Pipeline.DefaultInstance.build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\DefaultInstance.cs:line 22
              at StructureMap.Pipeline.Instance.createRawObject(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 103
              at StructureMap.Pipeline.Instance.Build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 69
              at StructureMap.Pipeline.ConstructorInstance.Get(String propertyName, Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 74
              at StructureMap.Pipeline.ConstructorInstance.Get[T](String propertyName, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 79
              at StructureMap.Pipeline.Arguments.Get[T](String propertyName) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Arguments.cs:line 18
              at lambda_method(Closure , IArguments )
              at StructureMap.Construction.BuilderCompiler.FuncCompiler`1.&lt;&gt;c__DisplayClass2.&lt;CreateBuilder&gt;b__0(IArguments args) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Construction\BuilderCompiler.cs:line 56
              at StructureMap.Construction.InstanceBuilder.BuildInstance(IArguments args) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Construction\InstanceBuilder.cs:line 34
              at StructureMap.Pipeline.ConstructorInstance.Build(Type pluginType, BuildSession session, IInstanceBuilder builder) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 237
              at StructureMap.Pipeline.ConstructorInstance.build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ConstructorInstance.cs:line 218
              at StructureMap.Pipeline.Instance.createRawObject(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 103
              at StructureMap.Pipeline.Instance.Build(Type pluginType, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\Instance.cs:line 69
              at StructureMap.Pipeline.ObjectBuilder.ConstructNew(Type pluginType, Instance instance, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ObjectBuilder.cs:line 39
              at StructureMap.Pipeline.ObjectBuilder.Resolve(Type pluginType, Instance instance, BuildSession session) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Pipeline\ObjectBuilder.cs:line 27
              at StructureMap.BuildSession.CreateInstance(Type pluginType, Instance instance) in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 176
              at StructureMap.BuildSession.&lt;&gt;c__DisplayClass3.&lt;.ctor&gt;b__1() in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 36
              at StructureMap.BuildSession.CreateInstance(Type pluginType) in c:\BuildAgent\work\767273992e840853\src\StructureMap\BuildSession.cs:line 215
              at StructureMap.Container.GetInstance(Type pluginType) in c:\BuildAgent\work\767273992e840853\src\StructureMap\Container.cs:line 265
              at Fables.Web.DependencyResolution.StructureMapDependencyScope.DoGetInstance(Type serviceType, String key) in f:\MyProjects\Fables\Fables\Fables.Web\DependencyResolution\StructureMapDependencyScope.cs:line 123
              at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) in c:\Projects\CommonServiceLocator\main\Microsoft.Practices.ServiceLocation\ServiceLocatorImplBase.cs:line 49
         InnerException: 
  </code></pre>
  
  <p>Can somebody explain please, what is this exception mean and how to resolve it? Ty.</p>