codeigniter login Cannot modify header information - codeigniter

Question

I test on my localhost is working well and now show any error but after upload to the godaddy server. it is codeigniter version 2.2.6.
this error show in the login page.
Error Message 1
Message: Cannot modify header information - headers already sent by (output started at /home/user/public_html/ngapali/test/application/controllers/admin/user.php:1)
Filename: libraries/Session.php
Line Number: 433
Error Message 2
Message: Cannot modify header information - headers already sent by (output started at /home/user/public_html/ngapali/test/application/controllers/admin/user.php:1)
Filename: libraries/Session.php
Line Number: 689
Admin Controller of My Controller
<?php
class Admin_Controller extends MY_Controller{
function __construct(){
parent::__construct();
$this->load->helper('form');
$this->load->library('form_validation');
$this->load->library('session');
$this->load->model('user_m');
$this->load->model('roomtype_m');
$this->load->model('room_m');
$this->load->model('roomcapacity_m');
//login check
$exception_uris = array(
'admin/user/login',
'admin/user/logout'
);
if(in_array(uri_string(), $exception_uris) == FALSE) {
if($this->user_m->loggedin() == FALSE) {
redirect('admin/user/login');
}
}
}}?>
My login page /user/login
Controller
<?php
class User extends Admin_Controller {
function __construct(){
parent::__construct();
}
public function index() {
$this->data['users'] = $this->user_m->get();
$this->data['subview'] = 'admin/user/index';
$this->load->view('admin/_layout_main',$this->data);
}
public function login() {
$dashboard = 'l0gadmin/dashboard';
$this->user_m->loggedin() == FALSE || redirect($dashboard);
$rules = $this->user_m->rules;
$this->form_validation->set_rules($rules);
if($this->form_validation->run() == TRUE){
if($this->user_m->login() == TRUE){
redirect($dashboard);
}else{
$this->session->set_flashdata('error','That email/password combination does not exist ');
redirect('admin/user/login','refresh');
}
}
$this->data['subview'] = 'admin/user/login';
$this->load->view('admin/_layout_modal',$this->data);
}
public function logout(){
$this->user_m->logout();
redirect('admin/user/login');
}}?>
Model
<?php
class User_m extends MY_Model {
function __construct(){
parent::__construct();
}
public function login(){
$user = $this->get_by(array(
'email'=> $this->input->post('email'),
'password' => $this->hash($this->input->post('password')),
),TRUE);
if(count($user)){
$data = array(
'name'=> $user->name,
'email' => $user->email,
'id'=> $user->id,
'loggedin'=>TRUE,
);
$this->session->set_userdata($data);
}
}
public function logout(){
$this->session->sess_destroy();
}
public function loggedin(){
return (bool) $this->session->userdata('loggedin');
}
public function hash($string){
return hash('sha512', $string . config_item('encryption_key'));
}}?>
View Page of login
<div class="row">
<div class="col-md-3">
<h2>Admin Login</h2>
<?php
echo validation_errors();
echo form_open('');
$email = array(
'name' => 'email',
'class' => 'form-control',
'placeholder' => 'Email Address'
);
echo form_input($email) . "<br/>";
$password = array(
'name' => 'password',
'class' => 'form-control',
'placeholder' => 'Password'
);
echo form_password($password) . "<br/>";
$submit = array(
'name' => 'submit',
'class' => 'form-control btn btn-primary',
'value' => 'Login'
);
echo form_submit($submit);
echo form_close();
?>
</div>
</div>
i search this problem can be of open and closed tag. I try to add all the page but it still show error. Why?.

Answer 1

Read the error message:
output started at
/home/user/public_html/ngapali/test/application/controllers/admin/user.php:1
/user.php file has some blank character on line 1
check for any blank space before <?php tag.
Remove it and refresh error will be go away.
One more suggestion,
Omit ending php tags ?> in controller and model files.
Read more here : Why would one omit the close tag?

Answer 2

This is most probably because there occured an error or warning, which is not visible because of your current display_errors setting. I would suggest turning it on in order to fix these errors/warnings.