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 ) {
		if ( ! isset( $updates[0]->response ) ) {
			if ( classicpress_is_dev_install() ) {
				echo '<h2>';
				_e( 'You are running a development version of ClassicPress.' );
				echo "</h2>\n";
				echo '<p>';
				_e( 'Development versions of ClassicPress do not receive automatic updates.' );
				echo "</p>\n";
			} else {
				echo '<h2>';
				_e( 'Unable to determine whether a ClassicPress update is available.' );
				echo "</h2>\n";
				echo '<p>';
				_e( 'You may be running a customized build of ClassicPress, or your server may be having internet connectivity problems.' );
				echo "</p>\n";
			}
		} else { // 'latest'
			echo '<h2>';
			_e( 'You have the latest version of ClassicPress.' );
			echo "</h2>\n";
		}

		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 '<p>';
			_e( 'Future security updates will be applied automatically.' );
			echo "</p>\n";
		}

	} else {
		echo '<div class="notice notice-warning"><p>';
		/* translators: 1: Link to Backups documentation page, 2: Link to Updating documentation page */
		printf(
			__( '<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 ClassicPress</a> documentation page.' ),
			'https://codex.wordpress.org/WordPress_Backups',
			'https://docs.classicpress.net/updating-classicpress/'
		);
		echo '</p></div>';

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

	if ( isset( $updates[0] ) && $updates[0]->response == 'development' ) {
		require_once ABSPATH . 'wp-admin/includes/class-wp-upgrader.php';
		$upgrader = new WP_Automatic_Updater;
		if ( $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 || $updates[0]->response != 'latest' ) ) {
		echo '<p>' . __( 'While your site is being updated, it will be in maintenance mode. As soon as your updates are complete, your site will return to normal.' ) . '</p>';
	} elseif ( ! $updates ) {
		echo '<p>' . sprintf(
			__( '<a href="%s">Learn more about ClassicPress %s</a>.' ),
			esc_url( self_admin_url( 'about.php' ) ),
			classicpress_version()
		) . '</p>';
	}
	dismissed_updates();
}