Exchange assignments are not allowed.

What causes this issue?

The fulfillment indicator is 'N' (= no assignment possible).

System Response

It is not possible to assign or display exchange assignments for
delivery item &V1& or shipment.

How to fix this error?

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.