No password has been provided but the backend requires one (in MD5)

Environment:

• Npgsql 3.1.2.0
• EntityFramework6.Npgsql 3.1.0

Code:

public void ExecuteQuery(string sqlQuery, Action<NpgsqlCommand> action)
{
            if (db.Database.Connection.State == ConnectionState.Open)
            {
                NpgsqlCommand command = new NpgsqlCommand(sqlQuery, (NpgsqlConnection)db.Database.Connection);

                action(command);
            }
            else
            {
                using (NpgsqlConnection conn = new NpgsqlConnection(db.Database.Connection.ConnectionString))
                {
                    conn.Open();

                    NpgsqlCommand command = new NpgsqlCommand(sqlQuery, conn);

                    action(command);

                    conn.Close();
                }
            }

 }

var sqlCommand = "SELECT [...]";

ExecuteQuery(sqlCommand, (command) =>
{
                var reader = command.ExecuteReader();

                while (reader.Read())
                {
                    id = reader[0] as long
                }
 });

Stacktrace:

 at Npgsql.NpgsqlConnector.ProcessAuthenticationMessage(String username, AuthenticationRequestMessage msg)

 at Npgsql.NpgsqlConnector.HandleAuthentication(String username, NpgsqlTimeout timeout)

 at Npgsql.NpgsqlConnector.Open(NpgsqlTimeout timeout)

 at Npgsql.ConnectorPool.Allocate(NpgsqlConnection conn, NpgsqlTimeout timeout)

 at Npgsql.NpgsqlConnection.OpenInternal()

 at Horus.Repositories.ContentBaseRepository.ExecuteQuery(String sqlQuery, Action`1 action)

Any ideas?

Thanks, Cristi