The material category &2 is assigned to the material &1

What causes this issue?

You wanted to perform a function that is not allowed for retail
materials. However, material &V1& is a retail material due to its
<DS:GLOS.material_category>material category</>.

System Response

The function may not be executed.

How to fix this error?

If necessary, correct your entry.

Error message extract from SAP system. Copyright SAP SE.