Acquia might need to place the Content Hub service in the maintenance mode. In this mode:

• Acquia temporarily suspends syndications and enqueues them.
• Content Hub does not allow you to register a new client if the site is not registered to the Content Hub service and attempts to connect to the service for the first time. Also, if the site is already registered to the service, the Register button is disabled.

For applications running Content Hub 3.4.0 or later, the system displays the following message in the Drupal admin user interface to indicate that the maintenance mode is enabled:

In the maintenance mode, the system does not execute any operation that:

• Involves the service directly
• Sends a request to the service at the time of its execution

The following are the examples of how operations are processed during the maintenance mode:

• Entity deletion is a direct Content Hub action. If you delete an entity during the maintenance mode, this operation is not propagated when the service resumes.
• Updates to existing or newly created entities do not involve the service directly. If you make updates to existing or newly created entities, the publisher enqueues the updates.