Admin 404 Log

// Admin 404 Log / Kiri Vadivelu / 2026

// Add admin menu

function add_404_log_menu() {

    add_menu_page(

        '404 Error Log',

        '404 Log',

        'manage_options',

        '404-log',

        'render_404_log_page',

        'dashicons-megaphone',

        80

    );

}

add_action( 'admin_menu', 'add_404_log_menu' );

// Render the page

function render_404_log_page() {

    global $wpdb;

    $table = $wpdb->prefix . '404_log';

    // Handle delete action

    if ( isset( $_GET['delete_id'] ) && check_admin_referer( 'delete_404_entry' ) ) {

        $wpdb->delete( $table, array( 'id' => intval( $_GET['delete_id'] ) ), array( '%d' ) );

        echo '<div class="notice notice-success"><p>Entry deleted.</p></div>';

    }

    // Handle clear all

    if ( isset( $_GET['action'] ) && $_GET['action'] === 'clear' ) {

        check_admin_referer( 'clear_404_log' );

        $wpdb->query( "TRUNCATE TABLE $table" );

        echo '<div class="notice notice-success"><p>All 404 logs cleared.</p></div>';

    }

    // Pagination

    $per_page = 50;

    $page     = max( 1, intval( $_GET['paged'] ?? 1 ) );

    $offset   = ( $page - 1 ) * $per_page;

    $total   = $wpdb->get_var( "SELECT COUNT(*) FROM $table" );

    $entries = $wpdb->get_results( $wpdb->prepare(

        "SELECT * FROM $table ORDER BY created_at DESC LIMIT %d OFFSET %d",

        $per_page, $offset

    ) );

    $pages = ceil( $total / $per_page );

    ?>

    // HTML container

    <div class="wrap">

        <h1>404 Error Log <span class="count">(<?php echo $total; ?>)</span></h1>

        <p>

            <a class="button" href="<?php echo wp_nonce_url( admin_url( 'admin.php?page=404-log&action=clear' ), 'clear_404_log' ); ?>"

               onclick="return confirm('Delete ALL 404 log entries?');">Clear All</a>

        </p>

        <table class="wp-list-table widefat fixed striped">

            <thead>

                <tr>

                    <th>Date</th>

                    <th>URL</th>

                    <th>Referrer</th>

                    <th>IP</th>

                    <th>User Agent</th>

                    <th>Action</th>

                </tr>

            </thead>

            <tbody>

            <?php if ( empty( $entries ) ) : ?>

                <tr><td colspan="6">No 404 errors logged.</td></tr>

            <?php else : foreach ( $entries as $e ) : ?>

                <tr>

                    <td><?php echo $e->created_at; ?></td>

                    <td><a href="<?php echo esc_url( $e->url ); ?>" target="_blank"><?php echo esc_html( $e->url ); ?></a></td>

                    <td><?php echo $e->referrer ? '<a href="' . esc_url( $e->referrer ) . '" target="_blank">' . esc_html( $e->referrer ) . '</a>' : '—'; ?></td>

                    <td><?php echo esc_html( $e->ip ); ?></td>

                    <td><?php echo esc_html( substr( $e->user_agent, 0, 60 ) ); ?>…</td>

                    <td>

                        <a href="<?php echo wp_nonce_url( admin_url( 'admin.php?page=404-log&delete_id=' . $e->id ), 'delete_404_entry' ); ?>"

                           onclick="return confirm('Delete this entry?');">Delete</a>

                    </td>

                </tr>

            <?php endforeach; endif; ?>

            </tbody>

        </table>

        <?php if ( $pages > 1 ) : ?>

            <div class="tablenav"><div class="tablenav-pages">

                <?php

                echo paginate_links( array(

                    'base'    => add_query_arg( 'paged', '%#%' ),

                    'format'  => '',

                    'current' => $page,

                    'total'   => $pages,

                ) );

                ?>

            </div></div>

        <?php endif; ?>

    </div>

    <?php

}    

// Log the 404 errors

function log_404_error() {

    if ( is_404() && ! is_admin() ) {

        global $wpdb;

        $table = $wpdb->prefix . '404_log';

        $wpdb->insert( $table, array(

            'url'        => esc_url_raw( home_url( $_SERVER['REQUEST_URI'] ) ),

            'referrer'   => esc_url_raw( $_SERVER['HTTP_REFERER'] ?? '' ),

            'ip'         => esc_sql( $_SERVER['REMOTE_ADDR'] ?? '' ),

            'user_agent' => esc_sql( substr( $_SERVER['HTTP_USER_AGENT'] ?? '', 0, 500 ) ),

            'created_at' => current_time( 'mysql' ),

        ) );

        // Keep only the last 200 entries

        $wpdb->query( "DELETE FROM $table WHERE id NOT IN (

            SELECT id FROM (

                SELECT id FROM $table ORDER BY created_at DESC LIMIT 200

            ) AS keep_ids

        )" );

    }

}

add_action( 'template_redirect', 'log_404_error', 1 );   

// Run once (e.g., on plugin/theme activation) to create the table

function create_404_log_table() {

    global $wpdb;

    $table = $wpdb->prefix . '404_log';

    $charset = $wpdb->get_charset_collate();

    $sql = "CREATE TABLE IF NOT EXISTS $table (

        id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,

        url VARCHAR(500) NOT NULL,

        referrer VARCHAR(500) DEFAULT '',

        ip VARCHAR(45) DEFAULT '',

        user_agent VARCHAR(500) DEFAULT '',

        created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,

        PRIMARY KEY (id),

        KEY url (url),

        KEY created_at (created_at)

    ) $charset;";

    require_once ABSPATH . 'wp-admin/includes/upgrade.php';

    dbDelta( $sql );

}

add_action( 'after_switch_theme', 'create_404_log_table' );

// Also run on init if table doesn't exist (safety net)

add_action( 'init', 'create_404_log_table' );