Obviously open_basedir is enabled and your phpBB folder is not included in it. You can add by creating a php.ini file containing:
Code: Select all
open_basedir = /path/to/your/phpbb
The other alternative is to disable open_basedir for your account. However, depending on your host's setup, modifying PHP settings can be done either through a php.ini file (as shown above), through an .htaccess file, or may even be forbidden.
This is why it would be best to contact your host for assistance. They know their setup and will be able to provide exact instructions on how to resolve the problem.