This issue is caused due to expired cpanel license or the corrupted license file.
It can be resolved by moving /var/cpanel/update_blocks.config and resynchronizing the cPanel license with /usr/local/cpanel/cpkeyclt.
# mv /var/cpanel/update_blocks.config /var/cpanel/update_blocks.config.bk
If its still the same, try to disable the CSF firewall by
# csf -x
and then resynchronizing the cPanel license.