Commands out of sync; you can't run this command now (with free_result())

My solution.

\system\database\DB_result.php 

....
public function result_array()
{
              .....
              is_null($this->row_data) OR $this->data_seek(0);
              if($this->conn_id->affected_rows > 0) {// My custom
                    while ($row = $this->_fetch_assoc())
                    {
                            $this->result_array[] = $row;
                    }
                    $this->free_result(); // My custom
                    @mysqli_next_result($this->conn_id); // My custom
              }

              return $this->result_array;
}