I have a controller.
public sealed class AccountsController : BaseApiController
{
private readonly IDatabaseAdapter _databaseAdapter;
I found a solution to this.
When I was building there was build warnings going to the output window but not showing in the main error / warning window.
They were to do with assembly conflicts and said recommend putting the assembly redirect in the web.Config.
Once I had went through them all (around 80) it now works.
e.g.
<dependentAssembly>
<assemblyIdentity name="System.Net.Http" culture="neutral" publicKeyToken="b03f5f7f11d50a3a" />
<bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.0.0" />
</dependentAssembly>