Pages in Plesk return Internal error: Failed to parse metadata, File aps_php.php

Symptoms

• The Plesk > Domains page cannot be opened due to the following error:

  external error: Failed to parse metadata

  Message Failed to parse metadata
  File aps_php.php
  Line 12559
  Type Exception

• The same error appears in an attempt to create/remove a customer/subscription.

• APS package settings cannot be checked:

  # /usr/local/psa/bin/aps -…