Unable to create a subscription or domain in Plesk: the IP pool is empty

Symptoms

• Unable to create subscription (Subscriptions > Add subscription) or domains (Domains > Add domain) with the following error:

  PLESK_WARN: Unable to create a subscription: the IP pool is empty.

  PLESK_ERROR: Unable to create a subscription because there are no shared IP addresses and no free dedicated IP addresses in Plesk

• Some of the packages are marked as not installed in Tools & Settings > Server Components or list is completely empty.

Cause

System packages were not configured.

Resolution

1. Connect to the server via SSH

2. Check the list of not configured packages: 

   # dpkg-query --list | grep -v "^ii"
   iU apache2 2.4.7-1ubuntu4.9 amd64 Apache HTTP Server 
   iU apache2-bin 2.4.7-1ubuntu4.9 amd64 Apache HTTP Server (binary files and modules)

3. Finish configuration of system packages:

   # dpkg --configure -a

4. Reinstall Plesk updates.
5. Browse to Tools & Settings > Server Components and click Refresh button to update information.