PHP Selector requires access to the native PHP version for proper work. It is specified in the file /etc/cl.selector/native.conf of the following content (example):
The file is created when installing CageFS on the servers with cPanel, Plesk, DA, Interworx and ISP Manager, if it is missing. On all other servers the file is not being created at all.
That is why, if the file is not created automatically, then it must be created manually and correct paths must be written to its directives.
Access permission 644 must be set:
chmod 0644 /etc/cl.selector/native.conf