Error when running Step-2-Managed-Opsworks-Base.json script - c06429364
No export named [CLIENT ]: PublicDomainOutput found
This error occurred because the customer who was being upgraded was having a new feature added. In this specific example, upon initial installation, there was no email service created for this customer.
Before the new OpsWorks stack can be created, update the [CLIENT] OpsWorks Stack to the latest Step-1-Managed-Client.json script
See - How to update an OpsWorks Stack article.