Entity Framework: There is already an open DataReader associated with this Command

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I am using Entity Framework and occasionally i will get this error. 

EntityCommandExecutionException
{"There is already an open DataReader associated with this Command which must be closed first."}
   at System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands...

Even though i am not doing any manual connection management.

this error happens intermittently.

code that triggers the error (shortened for ease of reading):

        if (critera.FromDate > x) {
            t= _tEntitites.T.Where(predicate).ToList();
        }
        else {
            t= new List<T>(_tEntitites.TA.Where(historicPredicate).ToList());
        }

using Dispose pattern in order to open new connection every time.

using (_tEntitites = new TEntities(GetEntityConnection())) {

    if (critera.FromDate > x) {
        t= _tEntitites.T.Where(predicate).ToList();
    }
    else {
        t= new List<T>(_tEntitites.TA.Where(historicPredicate).ToList());
    }

}

still problematic

why wouldn’t EF reuse a connection if it is already open.

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