If you have SELinux enabled, this advice from 06S01at14163 itservice is excellent. You may find that your next problem after configuring SELinux to allow write access to $CFG->dataroot will be a database connection failure. If so, you will need to configure SELinux to allow httpd to connect to your database with this command:
setsebool -P httpd_can_network_connect_db onI also recommend this article from Red Hat and this article from Oracle for more on how to succeed with SELinux on LAMP servers.