How to Redirect a 404 Error in a Custom 404 Page Using Codeigniter

How can I redirect a 404 Error in a custom 404 page using Codeigniter?

there is another way which I use: by overriding Exception core class of Codeigniter. Firstly make sure your config file(system/application/config/config.php) subclass prefix is as following
$config['subclass_prefix'] = 'MY_';

Then make a file named MY_Exceptions.php in system/application/libraries. Then override the function show_404() function here as follows.

class MY_Exceptions extends CI_Exceptions{
    function MY_Exceptions(){
        parent::CI_Exceptions();
    }

    function show_404($page=''){    

        $this->config =& get_config();
        $base_url = $this->config['base_url'];

        $_SESSION['error_message'] = 'Error message';
        header("location: ".$base_url.'error.html');
        exit;
    }
}

Now Error controller will be your error page, where the page will be redirected for 404 error.

How to Custom 404 Page Not Found in CodeIgniter 4

Go to your Routes.php file and find

$routes->set404Override();

Now , If you want to display just an error message then write

    $routes->set404Override(function(){
    echo "your error message";
});

instead of

$routes->set404Override();

Or
If you want to return a view then write like below:

$routes->set404Override(function(){
    return view('your_filename');
});

instead of

$routes->set404Override();

Codeigniter Custom 404 Page for different Controllers

Set up a custom 404 controller in the application/config/routes.php file.

$route['404_override'] = 'my404controller';

Create a My404controller and handle all the 404 errors in the index() using $this->uri->segment(0).

<?php defined('BASEPATH') OR exit('No direct script access allowed');

  class My404controller extends CI_Controller {

  function __construct() {
    parent::__construct();
  }

  public function index() {

  // $this->uri->segment(1) is *original* controller segment before routing.

  set_status_header(404); // set 404 header

  if ($this->uri->segment(1) == 'home') {
     $this->load->view('home/home404');
     return;
  }

  if ($this->uri->segment(1) == 'admin') {
     $this->load->view('admin/admin404');
     return;
  }

  if ($this->uri->segment(1) == 'blog') {
     $this->load->view('blog/blog404');
     return;
  }

  // If there's no match to existing controller, default to generic 404 page view.
  $this->load->view('default404');

  }
}

codeigniter 3.0 custom 404 not found error page

You need to set in application/config/routes.php the following route

$route['404_override'] = 'my404';

Then you need to create a new controller in your controllers directory (application/controllers/)

<?php 
class My404 extends CI_Controller 
{
 public function __construct() 
 {
    parent::__construct(); 
 } 

 public function index() 
 { 
    $this->output->set_status_header('404'); 
    $this->load->view('err404');//loading in custom error view
 } 
}

And create an err404 view. Thats all!

Refer :Reserved Routes

Codeigniter & PHP - forcing a 404?

show_404() actually sends the proper headers for a search engine to register it as a 404 page (it sends 404 status).

Use a Firefox addon to check the headers received when calling show_404(). You will see it sends the proper HTTP Status Code.

Check the default application/errors/error_404.php. The first line is:

<?php header("HTTP/1.1 404 Not Found"); ?>

That line sets the HTTP Status as 404. It's all you need for the search engine to read your page as a 404 page.

page redirect issue codeigniter : 404 error

Change your .htaccess file. Paste this in .htaccess in your app directory (in same level to applications) and will works :

RewriteEngine on
RewriteCond $1 !^(index\.php|resources|robots\.txt)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L,QSA]

And in conf.php:

$config['base_url'] = 'http://'.$_SERVER['SERVER_NAME'].':'.$_SERVER['SERVER_PORT'].'/stock-v2/';
$config['index_page'] = '';
$config['uri_protocol'] = 'REQUEST_URI';

Then use regirect like this without refresh:

redirect(base_url('dashboard'));

Check in http.conf do you allow override for your domain?

<Directory "/var/www">
    AllowOverride All
    # Allow open access:
    Require all granted
</Directory>

Codeigniter 4 - how to show 404 page?

I was looking just now exactly for the same thing.
I found here the solution: CodeIgniter 4 User Guide - Error Handling

In your controller, simply write:

throw \CodeIgniter\Exceptions\PageNotFoundException::forPageNotFound();