title: Could not load type 'ServiceStack.ServiceHost.IService' when starting ServiceStack
body: <p>I get the above error when calling Init() on my AppHost.</p>
  
  <p>This is on a clean asp.net v 4.5 empty web application with a simple HelloWorld service as per the getting started tutorial.</p>
  
  <p>I'm specifically using the older version of ServiceStack installed with:</p>
  
  <pre><code>Install-Package ServiceStack -Version 3.9.71
  </code></pre>
  
  <p>Which installs references to:</p>
  
  <pre><code>ServiceStack.dll 3.9.70.0
  ServiceStack.Common.dll 3.9.9.0
  ServiceStack.Interfaces.dll 3.9.9.0
  ServiceStack.OrmLite.dll 3.9.14.0
  ServiceStack.OrmLite.SqlServer.dll 1.0.0.0
  ServiceStack.Redis.dll 3.9.11.0
  ServiceStack.ServiceInterface.dll 3.9.70.0
  ServiceStack.Text.dll 4.0.11.0
  </code></pre>
  
  <p>And the error I get is:</p>
  
  <pre><code>[TypeLoadException: Could not load type 'ServiceStack.ServiceHost.IService' from assembly 'ServiceStack.Interfaces, Version=3.9.9.0, Culture=neutral, PublicKeyToken=null'.]
     Falck.WebAPI.AppHost..ctor() in c:\inetpub\wwwroot\WebAPI\Falck.WebAPI\Global.asax.cs:17
     Falck.WebAPI.Global.Application_Start(Object sender, EventArgs e) in c:\inetpub\wwwroot\WebAPI\Falck.WebAPI\Global.asax.cs:29
  
  [HttpException (0x80004005): Could not load type 'ServiceStack.ServiceHost.IService' from assembly 'ServiceStack.Interfaces, Version=3.9.9.0, Culture=neutral, PublicKeyToken=null'.]
     System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +9865825
     System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +118
     System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +172
     System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +336
     System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +296
  
  [HttpException (0x80004005): Could not load type 'ServiceStack.ServiceHost.IService' from assembly 'ServiceStack.Interfaces, Version=3.9.9.0, Culture=neutral, PublicKeyToken=null'.]
     System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9880168
     System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +101
     System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +254
  </code></pre>
  
  <p>It says it can't load the type, but I've no idea why?</p>
  
  <p>Below is the output from nuget:</p>
  
  <pre><code>Package Manager Console Host Version 2.8.50126.400
  
  Type 'get-help NuGet' to see all available NuGet commands.
  
  PM&gt; Install-Package ServiceStack -Version 3.9.71
  Attempting to resolve dependency 'ServiceStack.Common (≥ 3.0 &amp;&amp; &lt; 4.0)'.
  Attempting to resolve dependency 'ServiceStack.Text'.
  Attempting to resolve dependency 'ServiceStack.Redis (≥ 3.0 &amp;&amp; &lt; 4.0)'.
  Attempting to resolve dependency 'ServiceStack.OrmLite.SqlServer (≥ 3.0 &amp;&amp; &lt; 4.0)'.
  Installing 'ServiceStack.Text 4.0.11'.
  You are downloading ServiceStack.Text from Service Stack, the license agreement to which is available at https://servicestack.net/terms. Check the package for additional dependencies, which may come with their own license agreement(s). Your use of the package and dependencies constitutes your acceptance of their license agreements. If you do not accept the license agreement(s), then delete the relevant components from your device.
  Successfully installed 'ServiceStack.Text 4.0.11'.
  Installing 'ServiceStack.Common 3.9.11'.
  Successfully installed 'ServiceStack.Common 3.9.11'.
  Installing 'ServiceStack.Redis 3.9.11'.
  Successfully installed 'ServiceStack.Redis 3.9.11'.
  Installing 'ServiceStack.OrmLite.SqlServer 3.9.14'.
  Successfully installed 'ServiceStack.OrmLite.SqlServer 3.9.14'.
  Installing 'ServiceStack 3.9.71'.
  Successfully installed 'ServiceStack 3.9.71'.
  Adding 'ServiceStack.Text 4.0.11' to Falck.WebAPI.
  Successfully added 'ServiceStack.Text 4.0.11' to Falck.WebAPI.
  Adding 'ServiceStack.Common 3.9.11' to Falck.WebAPI.
  Successfully added 'ServiceStack.Common 3.9.11' to Falck.WebAPI.
  Adding 'ServiceStack.Redis 3.9.11' to Falck.WebAPI.
  Successfully added 'ServiceStack.Redis 3.9.11' to Falck.WebAPI.
  Adding 'ServiceStack.OrmLite.SqlServer 3.9.14' to Falck.WebAPI.
  Successfully added 'ServiceStack.OrmLite.SqlServer 3.9.14' to Falck.WebAPI.
  Adding 'ServiceStack 3.9.71' to Falck.WebAPI.
  Successfully added 'ServiceStack 3.9.71' to Falck.WebAPI.
  </code></pre>