Upgrade Dokuwike to a new version does take the webpage offline. You see the error message: The datadir ('pages') at ./data/pages is not found, isn't accessible or writable. You should check your config and permission settings. The reason for this is that the /usr/local/www/dokuwiki directory is set to root as owner and therefor the webserver cannot write to folder /usr/local/www/dokuwiki/data. Please change ownership for folder /usr/local/www/dokuwiki/data to www. Maybe you can add it to the port: chown -R www /usr/local/www/dokuwiki/data/
(In reply to idefix from comment #0) It's a VERY bad idea to have your wiki data located under the application directory. They should always be separate from the application. You should place the 'data' to somewhere else, which can be done by modifying savedir in conf/local.php.