public function handle_registration() {

    /*
     * Only process the supplier registration form.
     */
    if ( 'POST' !== $_SERVER['REQUEST_METHOD'] ) {
        return;
    }

    if ( ! isset( $_POST['hqsh_register_supplier'] ) ) {
        return;
    }

    /*
     * Verify security nonce.
     */
    if (
        ! isset( $_POST['hqsh_registration_nonce'] ) ||
        ! wp_verify_nonce(
            sanitize_text_field(
                wp_unslash( $_POST['hqsh_registration_nonce'] )
            ),
            'hqsh_supplier_registration'
        )
    ) {
        wp_die(
            'Security verification failed. Please refresh the registration page and try again.'
        );
    }

    /*
     * Get submitted information.
     */
    $name = isset( $_POST['hqsh_name'] )
        ? sanitize_text_field(
            wp_unslash( $_POST['hqsh_name'] )
        )
        : '';

    $email = isset( $_POST['hqsh_email'] )
        ? sanitize_email(
            wp_unslash( $_POST['hqsh_email'] )
        )
        : '';

    $username = isset( $_POST['hqsh_username'] )
        ? sanitize_user(
            wp_unslash( $_POST['hqsh_username'] )
        )
        : '';

    $password = isset( $_POST['hqsh_password'] )
        ? (string) $_POST['hqsh_password']
        : '';

    $password_confirm = isset( $_POST['hqsh_password_confirm'] )
        ? (string) $_POST['hqsh_password_confirm']
        : '';

    /*
     * Required fields.
     */
    if (
        empty( $name ) ||
        empty( $email ) ||
        empty( $username ) ||
        empty( $password ) ||
        empty( $password_confirm )
    ) {
        wp_die( 'Please complete all required fields.' );
    }

    /*
     * Validate email.
     */
    if ( ! is_email( $email ) ) {
        wp_die( 'Please enter a valid email address.' );
    }

    /*
     * Check username.
     */
    if ( username_exists( $username ) ) {
        wp_die( 'This username already exists. Please choose another username.' );
    }

    /*
     * Check email.
     */
    if ( email_exists( $email ) ) {
        wp_die( 'This email address is already registered.' );
    }

    /*
     * Check password length.
     */
    if ( strlen( $password ) < 8 ) {
        wp_die( 'Password must contain at least 8 characters.' );
    }

    /*
     * Check password confirmation.
     */
    if ( $password !== $password_confirm ) {
        wp_die( 'Passwords do not match.' );
    }

    /*
     * Create WordPress user.
     */
    $user_id = wp_create_user(
        $username,
        $password,
        $email
    );

    /*
     * Check for WordPress error.
     */
    if ( is_wp_error( $user_id ) ) {
        wp_die(
            esc_html(
                $user_id->get_error_message()
            )
        );
    }

    /*
     * Update user's name.
     */
    wp_update_user(
        array(
            'ID'           => $user_id,
            'display_name' => $name,
            'first_name'   => $name,
        )
    );

    /*
     * Assign supplier role.
     */
    $user = new WP_User( $user_id );

    if ( get_role( 'hq_supplier' ) ) {

        $user->set_role( 'hq_supplier' );

    } else {

        wp_die(
            'Supplier role "hq_supplier" does not exist. Please activate the HQ Supplier Hub role system.'
        );
    }

    /*
     * Redirect to Supplier Login.
     */
    $login_url = home_url( '/supplier-login/' );

    wp_safe_redirect( $login_url );

    exit;
}<br />
<b>Fatal error</b>:  Uncaught Error: Class &quot;HQSH_Registration&quot; not found in /home/u971076814/domains/hqmarketplacee.com/public_html/wp-content/plugins/hq-suppliers-hub/includes/Core/class-loader.php:73
Stack trace:
#0 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-content/plugins/hq-suppliers-hub/includes/Core/class-loader.php(37): HQSH_Loader-&gt;init_classes()
#1 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-content/plugins/hq-suppliers-hub/includes/Core/class-loader.php(23): HQSH_Loader-&gt;__construct()
#2 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-content/plugins/hq-suppliers-hub/hq-supplier-hub.php(72): HQSH_Loader::instance()
#3 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-includes/class-wp-hook.php(341): {closure}()
#4 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-includes/class-wp-hook.php(365): WP_Hook-&gt;apply_filters()
#5 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-includes/plugin.php(522): WP_Hook-&gt;do_action()
#6 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-settings.php(622): do_action()
#7 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-config.php(122): require_once('/home/u97107681...')
#8 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-load.php(50): require_once('/home/u97107681...')
#9 /home/u971076814/domains/hqmarketplacee.com/public_html/wp-blog-header.php(13): require_once('/home/u97107681...')
#10 /home/u971076814/domains/hqmarketplacee.com/public_html/index.php(17): require('/home/u97107681...')
#11 {main}
  thrown in <b>/home/u971076814/domains/hqmarketplacee.com/public_html/wp-content/plugins/hq-suppliers-hub/includes/Core/class-loader.php</b> on line <b>73</b><br />