How can I implement a custom error page in WordPress?

Creating a Custom 404 Error Page in WordPress

Basic Method: Using Theme Files

The simplest way to create a custom 404 page is by adding a 404.php file to your theme. WordPress automatically uses this file when a page isn't found.

Basic 404.php template example:

<?php get_header(); ?>

<div class="error-page">
    <h2>Page Not Found</h2>
    <p>Sorry, the page you're looking for doesn't exist.</p>
    
    <?php get_search_form(); ?>
    
    <div class="suggested-content">
        <h3>You might be interested in:</h3>
        <?php
        wp_get_archives(['type' => 'postbypost', 'limit' => 5]);
        ?>
    </div>
</div>

<?php get_footer(); ?>

Advanced Method: Custom Template with Hooks

Create a more dynamic 404 page with custom functionality:

<?php
// Add this to functions.php
function custom_404_actions() {
    if (is_404()) {
        // Log 404 errors
        error_log('404 Error: ' . $_SERVER['REQUEST_URI']);
        
        // Notify admin if needed
        if (strpos($_SERVER['REQUEST_URI'], '/important/') !== false) {
            wp_mail(
                get_option('admin_email'),
                '404 Error on Important Page',
                'Someone tried accessing: ' . $_SERVER['REQUEST_URI']
            );
        }
    }
}
add_action('template_redirect', 'custom_404_actions');

Best Practices

1. Content Elements to Include

   • Clear error message
   • Search box
   • Navigation menu
   • Links to popular content
   • Contact information
   • Back to home button

2. SEO Considerations

   • Set proper 404 HTTP header
   • Keep URLs unchanged
   • Monitor 404 errors
   • Add proper meta robots tags

3. Performance Tips

   • Keep the page light
   • Cache the page
   • Minimize redirects

Security Considerations

Prevent information disclosure with this code:

// Add to functions.php
function secure_404_page() {
    if (is_404()) {
        // Remove version info
        remove_action('wp_head', 'wp_generator');
        
        // Disable XML-RPC
        add_filter('xmlrpc_enabled', '__return_false');
        
        // Remove unwanted headers
        header_remove('X-Powered-By');
    }
}
add_action('template_redirect', 'secure_404_page');

Common Pitfalls to Avoid

1. Don't redirect all 404s to homepage
2. Avoid automatic redirects to similar pages
3. Don't use session storage for 404 tracking
4. Keep error messages user-friendly

Recommended Plugins

1. 404page - Simple custom 404 page creator

   • WordPress Plugin Directory
   • Features visual editor and custom layouts

2. Redirection - Manage 404 errors and redirects

   • WordPress Plugin Directory
   • Tracks 404 errors and sets up redirects

Additional Tips

Track 404 errors with this analytics code:

// Add to functions.php
function track_404_errors() {
    if (is_404()) {
        if (function_exists('ga_tracking_code')) {
            ?>
            <script>
                gtag('event', '404_error', {
                    'event_category': 'Error Pages',
                    'event_label': window.location.href
                });
            </script>
            <?php
        }
    }
}
add_action('wp_footer', 'track_404_errors');

Remember to test your 404 page regularly and update content based on user behavior and common error patterns.