On subdomains installations if the configuration php.ini file of PHP, have the open_basedir directive active, wp_w3all will not include the necessary phpBB config file, because files inclusions are restricted to the directory assigned by open_basedir in the server, and the phpBB config file inclusion from another directory (that are in this case domain or subdomain) won’t work.
To let wp_w3all include the config file between domains and subdomains on your server, you need to comment off the open_basedir in your php.ini in this way:
;open_basedir = …
and restart Apache
or in apache httpd.conf add something like:
php_admin_value open_basedir none
On online servers you need to edit the php.ini file under your domain control panel:
“my host uses Odin/plesk hosting software and through that i found a phpsetting tab, allowing me to change open_basedir.
and that solved it.”
NOTE about security implications: it is assumed here, that you know what about security, if server folders aren’t under control of same user.