Redirect Restricted Page to 404

Is there a way to show a 404 page if the current logged in user does not have the right clearance to view the page? I am looking for a PHP method, something like

if( !current_user_can('administrator') ) { show_404(); exit(); }

I have thought about using a redirect, but I would like to keep the url the same.

Answers:

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Method 1

I was able to display a 404 error by using the following code in my header.

<?php
  global $wp_query;
  $wp_query->set_404();
  status_header( 404 );
  get_template_part( 404 ); exit();
?>

To break it down:
$wp_query->set_404(): tells the wp_query this is a 404, this changes the title
status_header(): sends a HTTP 404 header
get_template_part(): displays the 404 template

Method 2

Why don’t you create a page that show error message and then redirect user to that page? Here is a simple way to achieve that:

Open the 404.php file and add these lines to the top of it:

/**
 * Template Name: 404 Page
 */

Create a page with 404 Page template. Then redirect users:

if ( !current_user_can('administrator') ) {
    $404_page = get_permalink( $404_page_id );
    wp_redirect( $404_page );
    exit();
}

The reason you should use a page for 404 request is: in WP 404 page actually is a page that doesn’t exists, WP has to search for all of its content before returning the 404 page and that work is a waste of resource. Using a pre-configured page that might help you run your blog faster.

Method 3

I had a similar requirement where I should not let users access the author.php page based on the role a user was in. I register the template_redirect action to do my checks and redirect to 404 page even before the actual page is loaded.

Registration:

add_action( 'template_redirect', [ $this, 'handle_inactive_users']);

Handler:

public function handle_inactive_users() {
    global $wp_query;
    if ( $wp_query->is_author() ) {
        $user = $wp_query->get_queried_object();
        if ( is_a( $user, WP_User::class ) && $user->has_cap( 'inactive' ) ) {
            $wp_query->set_404();
            status_header( 404 );
            get_template_part( 404 );
            exit();
        }
    }
}

If you chose to only use the following code snippet in the middle of template part, the page may have already been rendered partially and you are not actually redirected to a 404 page. So better to do it in the template_redirect action –

$wp_query->set_404();
status_header( 404 );
get_template_part( 404 );
exit();

Method 4

You can write this code to file 404.php in actually used theme directory (wp-content/themes/…./404.php):

<?php
header("HTTP/1.1 301 Moved Permanently");
header("Location: ".get_bloginfo('url'));
exit();
?>

This code must start from begin of file (without any characters before).

Link to original: How to Redirect your 404 page to the Home Page in WordPress

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0