title: Error in Visual Studio 2013: "No exports were found that match the constraint"
body: <p>I don't know what happen with my Visual&nbsp;Studio&nbsp;2013 Update 2.</p>
  
  <p>When I opened my project, it displayed this message:</p>
  
  <blockquote>
    <p>No exports were found that match the constraint:
    ContractName</p>
    
    <p>Microsoft.Internal.VisualStudio.PlatformUI.ISolutionAttachedCollection.Service</p>
    
    <p>RequiredTypeIdentity <br/>
      Microsoft.Internal.VisualStudio.PlatformUI.ISolutionAttachedCollection.Service</p>
  </blockquote>
  
  <p>I am really confused. I've tried <a href="https://stackoverflow.com/questions/17984580/getting-error-in-no-valid-exports-were-found-that-match-the-constraint">this solution</a>, but it didn't solve my problem...</p>