Key attribute &1 will be added from entity &2

What causes this issue?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

System Response

In case of ruleset generation, key attribute of an entity is added to
the view and ruleset when an entity is selected on the UI though this
attribute might not be selected explicitly on the UI. When multipe
entities are chosen on the UI having the same key attribute, the system
is not able to identify from which entity, this key attribute should be
selected and added to the view

How to fix this error?

To aviod having duplicate keys in the Hana views, the key attribute
should be exposed from one of the entity. In order to acheive this,
select only one entity which has this as key attribute

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.