Are you getting following error in apache error logs?
Warning: main(): open_basedir restriction in effect.
That means php open_basedir protection is turned on in the server.
You need to turn it off by making an “exception” for this.
To make the exception, log in to WHM, click “Tweak Security”, then click “configure” below “Php open_basedir Tweak”.
Now place a check mark beside the domain in question (exclude protection box) and hit save.
This should clear up the php open base problem.
