EntityStorageException: The entity URI 'entity:node/' is invalid

Problem/Motivation

Drupal\Core\Entity\EntityStorageException: The entity URI 'entity:node/' is invalid. You must specify the entity id in the URL. e.g., entity:node/1 for loading the canonical path to node entity with id 1. in Drupal\Core\Entity\Sql\SqlContentEntityStorage->save() (line 815 of core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php).

Steps to reproduce

Create a child page on a node

Proposed resolution

TBD

Remaining tasks

TBD

User interface changes

TBD

API changes

TBD

Data model changes

TBD