A different supplier category (internal/external) assigned in ref. plant

What causes this issue?

A vendor category (internal/external vendor) that differs from the
vendor category of the reference plant was found for plant &V4&,
material &V2& in unit of measure &V3&.

System Response

Price activation at plant group level may lead to incorrect results for
plant group &V1&.

How to fix this error?

You can activate prices at plant level by changing the price activation
type of plant group &V1&. To do this, change the price activation type
indicator to "Plant" in the plant group overview.

Error message extract from SAP system. Copyright SAP SE.