EPiServer 7: There is already an open DataReader associated with this Command which must be closed first.

I ran into the following error on an EPiServer 7 Preview site today:

“There is already an open DataReader associated with this Command which must be closed first.”

The problem is that EPiServer 7 requires that the MultipleActiveResultSets is set to true in the connection string.

ConnectionStrings.config:

<connectionStrings>

  <clear />

  <add name="EPiServerDB" 

       connectionString="Data Source=(local)\SQLEXPRESS;

         Initial Catalog=epi;

         Integrated Security=False;

         User ID=user;

         Password=pwd;

         MultipleActiveResultSets=True" 

       providerName="System.Data.SqlClient" />

</connectionStrings>