Your system is missing the file /etc/fstab.

You may get the following warning when you try to install WHM into your server.

Your system is missing the file /etc/fstab. This is an essential system file that is part of the base system.
Please ensure the system has been properly installed.

Here are the solution.

#cat /proc/mounts > /etc/fstab
#chmod 644 /etc/fstab