Can't install or update Plesk: there is no product with the ID 'plesk' at the installation source

Symptoms

• Plesk fails to install or update with one of these errors:

  ERROR: There is no product with the ID 'plesk' at the installation source.

  ERROR: There is no release with ID 'PLESK_XX_X_XX' of product 'plesk' at the installation source.

• Installation is interrupted with a message like this one:

  Installation will not continue because of your operating system
  "'Centos' 'Linux' '6 .4 '' x86_64 '" is not supported.
  Please see the Plesk release notes for the full list of
  supported operating systems.

Cause

The server has an unsupported operating system.

Resolution

Dist-Upgrade or migrate the server to a supported operating system.