Post 500 (Internal Server error) ajax in codeigniter - ajax

Question

I have a problem to sending data with ajax, when i click button save to sending data to database. but when i push F12 the error show
POST http://[::1]/sys-web/admlogin/manufacture/addmanufacture 500 (Internal Server Error)
send # http://[::1]/sys-web/assets/js/jquery-2.1.4.min.js:4
ajax # http://[::1]/sys-web/assets/js/jquery-2.1.4.min.js:4
save # http://[::1]/sys-web/admlogin/manufacture:374
onclick # http://[::1]/sys-web/admlogin/manufacture:507
CI Controller
public function AddManufacture()
{
$data = array(
'manufacturing_name' => $this->input->post('manufacturing_name'),
'address' => $this->input->post('address'),
'email' => $this->input->post('email'),
'telephone' => $this->input->post('telephone'),
'join_date' => $this->input->post('join_date')
);
$insert = $this->m_manufacture->save($data);
echo json_encode(array("status" => TRUE));
}
CI Model :
function save($data)
{
$sql = $this->db->insert($this->table, $data);
return $sql;
}
CI View :
function save()
save_method = 'add';
{
$('#btnSave').text('saving...'); //change button text
$('#btnSave').attr('disabled',true); //set button disable
var url;
if(save_method == 'add') {
url = "<?php echo site_url('admlogin/manufacture/addmanufacture')?>";
} else {
url = "<?php echo site_url('admlogin/manufacture/editmanufacture')?>";
}
// ajax adding data to database
var formData = new FormData($('#form')[0]);
$.ajax({
url : url,
type: "POST",
data: formData,
contentType: false,
processData: false,
dataType: "JSON",
success: function(data)
{
if(data.status) //if success close modal and reload ajax table
{
$('#modal_form').modal('hide');
reload_table();
}
else
{
for (var i = 0; i < data.inputerror.length; i++)
{
$('[name="'+data.inputerror[i]+'"]').parent().parent().addClass('has-error'); //select parent twice to select div form-group class and add has-error class
$('[name="'+data.inputerror[i]+'"]').next().text(data.error_string[i]); //select span help-block class set text error string
}
}
$('#btnSave').text('save'); //change button text
$('#btnSave').attr('disabled',false); //set button enable
},
error: function (jqXHR, textStatus, errorThrown)
{
alert('Error adding / update data');
$('#btnSave').text('save'); //change button text
$('#btnSave').attr('disabled',false); //set button enable
}
});
}