Sometimes you need to remove limits that are automatically added by DirectAdmin. For example, you are not allowed to include files from anywhere but your home directory, you cannot use CURLOPT_FOLLOWLOCATION in php and so on.
The first case is the result of open_basedir protection. If you’re not running a hosting service and all sites are yours, it is enough safe to disable open_basedir protection for you own sites if you really need it. Safe mode may prevent you from running some scripts and you might also need to turn it off. This can be done from Directadmin Admin Panel. Just follow the screenshot below:
Then you should find your domain and disable open_basedir and safe mode for it. I usually disable these protections by default, but I don’t recommend to do it when you run a hosting service.
Don’t forget to restart Apache after your changes as they will be propagated upon httpd restart only. It will be done automatically in some time, but if you need it instantly, you should reboot it manually.