Substitute loc. &1 is not a production plant - production not possible

What causes this issue?

Substitute location &V1& has category &V2&. Such a location usually
cannot produce.
You have chosen &V3& as substitution activity. The activity starts
production in the substitute plant (BOMEX = &V4&).

System Response

The system cannot start production in a location with category &V2&,
and will ignore the indicator.

How to fix this error?

Choose a different activity (using BOMEX = '0' ) or
Choose a different substitute location (category '1001').

Error message extract from SAP system. Copyright SAP SE.