Unit of measure &3 for material &1 only has generated EAN/UPC &2

What causes this issue?

Unit of measure &v3& for material &v1& does not have an EAN/UPC. As an
EAN/UPC is needed for price catalog maintenance, EANUPC &v2& was
generated.

System Response

The catalog item cannot be transferred.

How to fix this error?

Maintain a valid EAN/UPC in material maintenance.

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.