Invalid argument supplied for foreach()

[eluser]SaSa[/eluser]
I have this error, How do I solve it?

Code:

A PHP Error was encountered
    Severity: Warning
    Message: Invalid argument supplied for foreach()
    Filename: admin/tour.php
    Line Number: 81

this is line 81:

Code:

$files = $this->multi_upload->go_upload();
            var_dump($files);
            $images = array();    
            foreach ($files as $img) {   //line 81
              $images[] = $img['file'];
            }
if (!$files)
        {
            //$error = array('error' => $this->upload->display_errors());
            //$this->load->view('admin/tour_foreign_insert', $error);
            //$data['error'] = $this->upload->display_errors();
            $this->session->set_flashdata('error', $this->upload->display_errors());
            //$this->load->view('admin/tour_foreign_insert',$data);
            //sleep(5);
            redirect('admin/tour/insert_foreign', 'refresh');
        }

With respect