Enter a valid primary key for CDS view &1.

What causes this issue?

A CDS view must contain the key fields of its parent. These key fields
are required to build the compositional association.

System Response

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

How to fix this error?

Procedure for System Administrators

Contact the corresponding developer of the CDS view to correct the
error.

Error message extract from SAP system. Copyright SAP SE.