1. Please force update using this command.

rm -f /usr/local/cpanel/Cpanel/rvversion

perl /root/rvadmin/auto_rvskin.pl

2. Go to root WHM >> Server Configuration >> Tweak Settings >> System >> “Accounts that can access a cPanel user account”, and mark at "Root, Account-Owner, and cPanel User"

If still not work, please SSH to your server and run following command.

cd /usr/lib/perl5/site_perl

ln -s 5.8.8 5.6.2