System.TypeLoadException: Method 'get_xxx' does not have an implementation
<p>There are a lot of questions floating around with this problem and i've worked through them ll with no joy.</p>

<p>I am receiving this error:</p>

<blockquote>
  <p>Method 'get_UserImageCDNUrl' in type 'App.Web.WebConfig' from assembly
  'App.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' does
  not have an implementation.</p>
</blockquote>

<p>Which is really strange because I am trying to run Api.Web which has no reference to App.Web, the only thing they have in common are references to other projects (Models.Domain and Models.DTO).</p>

<p>I have an interface:</p>

<p><strong>IResourceCompiler</strong> in an assembly "Models.Domain"</p>

<p>I have an abstract class which implements this interface in the same assembly (Models.Domain) called <strong>WebConfigBase</strong></p>

<p>In the "App.Web" and "Api.Web" projects they each have a class called <strong>WebConfig</strong> which inherit from <strong>WebConfigBase</strong>, therefore both <strong>WebConfig</strong> classes in App and Api are implementations of <strong>IResourceCompiler</strong>.</p>

<p>I tried to add a property </p>

<pre><code>string UserImageCDNUrl {get;}
</code></pre>

<p>to <strong>IResourceCompiler</strong> and added the property to <strong>WebConfigBase</strong></p>

<pre><code>public string UserImageCDNUrl 
{
    get { return ""; } 
}
</code></pre>

<p>so the property would be accessible to both Api and Web projects through their own <strong>WebConfig</strong> classes, and i get the exception above.</p>

<p>I have looked for hours to try and see why this happens with no joy.</p>

<p>I've cleared my Obj folders, cleaned, rebuilt, checked for any instances in GAC (there aren't any) and i'm still stuck on this.</p>

<p>Everything works fine until i try to add a new property to the interface (and base class)</p>