If you are running ispconfig + nginx + php-fpm and have such error:

FastCGI sent in stderr: “PHP message: PHP Warning: Unknown: open_basedir restriction in effect. File(/var/www/clients/client0/webXXX/web/index.php) is not within the allowed path(s):

Fix.

You need check your nginx virtual host:

/etc/nginx/sites-enabled/100-linuxėyou.tk.vhost
line
fastcgi_pass = some_ip:PORT

grepp PORT /etc/php5/fpm/pool.d/webXXX.conf

/etc/init.d/nginx restart