core_upgrade_preamble

function core_upgrade_preamble() {
	global $required_php_version, $required_mysql_version;

	$wp_version = get_bloginfo( 'version' );
	$updates    = get_core_updates();

	if ( ! isset( $updates[0]->response ) || 'latest' === $updates[0]->response ) {
		echo '<h2>';
		_e( 'You have the latest version of WordPress.' );

		if ( wp_http_supports( array( 'ssl' ) ) ) {
			require_once ABSPATH . 'wp-admin/includes/class-wp-upgrader.php';
			$upgrader            = new WP_Automatic_Updater;
			$future_minor_update = (object) array(
				'current'       => $wp_version . '.1.next.minor',
				'version'       => $wp_version . '.1.next.minor',
				'php_version'   => $required_php_version,
				'mysql_version' => $required_mysql_version,
			);
			$should_auto_update  = $upgrader->should_update( 'core', $future_minor_update, ABSPATH );
			if ( $should_auto_update ) {
				echo ' ' . __( 'Future security updates will be applied automatically.' );
			}
		}
		echo '</h2>';
	}

	if ( isset( $updates[0]->version ) && version_compare( $updates[0]->version, $wp_version, '>' ) ) {
		echo '<div class="notice notice-warning"><p>';
		printf(
			/* translators: 1: Documentation on WordPress backups, 2: Documentation on updating WordPress. */
			__( '<strong>Important:</strong> Before updating, please <a href="%1$s">back up your database and files</a>. For help with updates, visit the <a href="%2$s">Updating WordPress</a> documentation page.' ),
			__( 'https://wordpress.org/support/article/wordpress-backups/' ),
			__( 'https://wordpress.org/support/article/updating-wordpress/' )
		);
		echo '</p></div>';

		echo '<h2 class="response">';
		_e( 'An updated version of WordPress is available.' );
		echo '</h2>';
	}

	if ( isset( $updates[0] ) && 'development' === $updates[0]->response ) {
		require_once ABSPATH . 'wp-admin/includes/class-wp-upgrader.php';
		$upgrader = new WP_Automatic_Updater;
		if ( wp_http_supports( 'ssl' ) && $upgrader->should_update( 'core', $updates[0], ABSPATH ) ) {
			echo '<div class="updated inline"><p>';
			echo '<strong>' . __( 'BETA TESTERS:' ) . '</strong> ' . __( 'This site is set up to install updates of future beta versions automatically.' );
			echo '</p></div>';
		}
	}

	echo '<ul class="core-updates">';
	foreach ( (array) $updates as $update ) {
		echo '<li>';
		list_core_update( $update );
		echo '</li>';
	}
	echo '</ul>';
	// Don't show the maintenance mode notice when we are only showing a single re-install option.
	if ( $updates && ( count( $updates ) > 1 || 'latest' !== $updates[0]->response ) ) {
		echo '<p>' . __( 'While your site is being updated, it will be in maintenance mode. As soon as your updates are complete, this mode will be deactivated.' ) . '</p>';
	} elseif ( ! $updates ) {
		list( $normalized_version ) = explode( '-', $wp_version );
		echo '<p>' . sprintf(
			/* translators: 1: URL to About screen, 2: WordPress version. */
			__( '<a href="%1$s">Learn more about WordPress %2$s</a>.' ),
			esc_url( self_admin_url( 'about.php' ) ),
			$normalized_version
		) . '</p>';
	}
	dismissed_updates();
}