wp_not_installed()

Source

File: wp-includes/load.php

function wp_not_installed() {
	if ( is_multisite() ) {
		if ( ! is_blog_installed() && ! wp_installing() ) {
			nocache_headers();

			wp_die( __( 'The site you have requested is not installed properly. Please contact the system administrator.' ) );
		}
	} elseif ( ! is_blog_installed() && ! wp_installing() ) {
		nocache_headers();

		require ABSPATH . WPINC . '/kses.php';
		require ABSPATH . WPINC . '/pluggable.php';

		$link = wp_guess_url() . '/wp-admin/install.php';

		wp_redirect( $link );
		die();
	}
}