Npgsql连接PG数据库报错

[cstslqq]

/// <summary>
        /// get dataset
        /// </summary>
        /// <param name="strSQL">(string)</param>
        /// <returns>(DataSet)</returns>
        public static DataSet Execute4Ds(string strSQL)
        {
            NpgsqlConnection myCn = new NpgsqlConnection(strPostgreConn);
            try
            {
                LogManage.LogError("open connection begin ");
                myCn.Open();
                LogManage.LogError("open connection success");
                NpgsqlDataAdapter sda = new NpgsqlDataAdapter(strSQL, myCn);
                DataSet ds = new DataSet("ds");
                sda.Fill(ds);
                LogManage.LogError("fill ds");
                return ds;
            }
            catch (NpgsqlException e)
            {
                LogManage.LogError(e.Message);
                throw new Exception(e.Message);
            }
            finally
            {
                myCn.Close();
            }
        }

Npgsql连接PG数据库报错：
The type initializer for 'NpgsqlTypes.NpgsqlTypesHelper' threw an exception.