We recently upgraded to 15.8 and we have a few processes which are using the aggregated attribute or a virtual attribute in the process start condition. If I try to save the process, I get a validation error on the aggregated attribute.
This is working as expected and due to a design change made starting in 15.4 where virtual attributes and aggregated calculated attributes are no longer supported in process start conditions.
This is referenced in section Process Conditions Cannot Include Virtual Attributes or ACA at Configure Processes:
Beginning with Release 15.4, a Task or Project object process condition cannot include a virtual attribute or aggregated calculated attribute. These attributes are no longer available for users to select in the expression builder when defining a process condition.
An upgraded or imported process with derived virtual or aggregated calculated attributes will throw a validation error only if the step containing the attribute is evaluated again and the entire process is validated. See the 15.4 Change Impact and Upgrade documentation.
The reason for this change is noted below as referenced in CA PPM 15.4 Change Impact and Upgrade (Section Process Conditions Cannot Include Virtual Attributes or ACAs):
"If a process built around the Task or Project primary object included a virtual attribute or ACA in its start condition, the user could no longer use Autoschedule. Selecting these attributes and running the process also caused issues in other areas. For example, the application could prevent you from saving tasks, task assignments, or team member records."
Release : Clarity 15.4 and higher
Component : CA PPM BUSINESS PROCESS MANAGEMENT
It's possible XOG will allow you to make changes to a process with these attribute types in the start condition, but this is not supported, since it's not supported to have these fields in the start condition of your process. You may see some negative side effects including performance or other issues.