Symptoms
It is not possible to view the hotfixes list from Home > System > Hotfixes - the page stays loading and fails by timeout, an error "Billing is not available now" may appear.
Cause
The problem is caused by an internal issue with id #PBA-56314, reproduced only on the servers with sudo version sudo-1.7.4p5-7.el6.x86_64.rpm.
Workaround
Modify file permissions on the PBA application server:
# cd /etc/sudoers.d/
# chmod 644 pba-hotfixes