Data model &1, entity type &2: No structure found for reference attribute

What causes this issue?

You have attempted to generate a structure for entity type &V4& in data
model &V1&.
The quantity or amount &V2& in this entity type references a unit of
measure or currency that is defined in entity type &V3&.
However, you have not entered the structure for entity type &V3& in the
list of structures to be generated. Therefore, the system has not
generated a structure for entity type &V3&.

System Response

The system cannot generate the structure for entity type &V4&.

How to fix this error?

Enter the structure for entity type &V3& in the list of structures to be
generated.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.