Make sure that static IPv4 address is preliminarily configured. If you have an environment that uses only IPv6 addresses, ensure the proper address translation to the IPv4 segment of the Internet.
Certain ports should be open. For details, see
http://kb.plesk.com/en/391.
The AppArmor app is disabled. For details, see
http://kb.plesk.com/en/112903.
The disk space allocated to the /tmp directory exceeds 100 megabytes.
If you run Debian, CloudLinux, or Ubuntu, make sure that you have system repositories with updates availiable to your package manager.