title: Visual Studio 2013 error creating an EDMX file
body: <p>In Visual Studio 2013 (Update 2, and later Update 4), using Entity Framework 6.1.2, I am having issues when creating an EDMX file.</p>
  
  <p>When creating the file, I add a new item, select "ADO.NET Entity Data Model", and regardless of whether I create an "Empty EF Designer model" or "EF Designer from database" (and regardless of which database I might chose if building off of a database) I receive a very generic error message: </p>
  
  <blockquote>
    <p>"Operation is not valid due to the current state of the object"</p>
  </blockquote>
  
  <p>and it kicks me back to the Add New Item wizard. The *.edmx is generated, but if I attempt to open the generated *.edmx file, I receive another generic message:</p>
  
  <blockquote>
    <p>"The operation could not be completed."</p>
  </blockquote>
  
  <p>The *.designer.cs file appears to be populated, but not all of the assembly references are added to the project; System.Data.Entity had to be added manually for references to System.Data.Objects to resolve.</p>
  
  <p>I have installed Entity Framework 6 Tools for Visual Studio 2012 &amp; 2013, for both versions of Visual Studio. I have tried performing this with the projects both bound to TFS as well as unbound, and the error persists in either situation.</p>
  
  <p>If I open the solution in Visual Studio 2012, the same errors persist. I am able to add an *.edmx file in Visual Studio 2010 successfully, and then <strong>later</strong> open the project in Visual Studio 2013, and the *.edmx file is present and accessible; it opens and I am able to view it, but if I move or edit, I am given the following error:</p>
  
  <blockquote>
    <p>"XmlModels involved in this transaction are not editable."</p>
  </blockquote>
  
  <p>Does anyone have any suggestions for that is happening, or what might be missing from my environment? I'm at a loss for what is improperly set up on my system.</p>