title: Visual Studio Entity-Framework-Designer: Update model from database broken by custom provider
body: <p>We have decorated the default Entity Framework provider to support custom ExpressionsVisitors. So far everything works out the way we intend it to be. </p>
  
  <p>After adding the custom provider entry into the machine.config and placing the Custom Provider Assembly in the machine’s GAC the entity framework designer was not broken any more and did show up correctly.</p>
  
  <p>However the command <code>“Update model from database...”</code> just ends in a message box stating that:</p>
  
  <pre><code>An exception of type 'Microsoft.VSDesigner.Data.Local.ConnectionStringConverterServiceException' occurred while attempting to update from the database. The exception message is: ''.
  </code></pre>
  
  <p>We’re using VS Premium 2012 with .net 4.5.</p>
  
  <p>Where does this error come from and what needs to be done to fix it?
  Any Help or Advice Gladly Appreciated</p>