问题升级到信号器2.0 asp.net webmatrix（OWIN）

Question

我知道signalr已经在2.0版本上转向了.net 4.5。我已经通过web.config将我的asp.net webmatrix升级到.net 4.5。但无法安装信号器2.0。 Owin引发了一个例外。这是我的web.config，接下来的bug。我错过了什么？ .net 4.5已安装。感谢

  <system.web>   
    <compilation debug="true" targetFramework="4.5"><assemblies><add assembly="System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" /></assemblies></compilation>
    <httpRuntime targetFramework="4.5" maxRequestLength="1048576" />
      <authentication mode="Forms">
      <forms timeout="1440" />
    </authentication>
     <sessionState timeout="1440"></sessionState>
  </system.web>

An error occurred.

Could not install package 'Microsoft.Owin.Security 2.0.0'. You are trying to install this package into a project that targets '.NETFramework,Version=v4.0.0.0', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.

System.InvalidOperationException: Could not install package 'Microsoft.Owin.Security 2.0.0'. You are trying to install this package into a project that targets '.NETFramework,Version=v4.0.0.0', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.
   at NuGet.ProjectManager.ExtractPackageFilesToProject(IPackage package)
   at NuGet.ProjectManager.AddPackageReferenceToProject(IPackage package)
   at NuGet.ProjectManager.Execute(PackageOperation operation)
   at NuGet.ProjectManager.Execute(IPackage package, IPackageOperationResolver resolver)
   at NuGet.ProjectManager.AddPackageReference(IPackage package, Boolean ignoreDependencies, Boolean allowPrereleaseVersions)
   at NuGet.ProjectManager.AddPackageReference(String packageId, SemanticVersion version, Boolean ignoreDependencies, Boolean allowPrereleaseVersions)
   at Microsoft.WebMatrix.PackageManagement.WebProjectManager.<>c__DisplayClass1.<InstallPackage>b__0()
   at Microsoft.WebMatrix.PackageManagement.WebProjectManager.PerformLoggedAction(Action action)
   at Microsoft.WebMatrix.PackageManagement.WebProjectManager.InstallPackage(IPackage package, Boolean ignoreDependencies, AppDomain appDomain)
   at Microsoft.WebMatrix.NuGet.NuGetPackageManager.InstallPackage(IPackage package)
   at Microsoft.WebMatrix.NuGet.NuGetModel.InstallPackage(IPackage package, Boolean inDetails)
   at Microsoft.WebMatrix.NuGet.PackageViewModel.Install()
   at System.Threading.Tasks.Task.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()