Few days back i got error Unable to install yum-rhn-plugin, please contact CloudLinux support at https://helpdesk.cloudlinux.com on one of our shared web hosting server while installing CloudLinux, I googled it but not able to found any proper solution, i have re-installed cPanel/WHM from scratch but no luck. This issue mostly appears on OVH Servers as they use their own cPanel/WHM and CentOS kernels which got few bugs in the repositories. I contacted cloudlinux support they provided me single command that fixed this issue immediately.
You can also run this command in SSH to fix out the repositories issue:
# rpm -e --nodeps libxml2-devel
Running up above command will fix this issue for sure as tested.