Not possible to configure a planning variant here

What causes this issue?

You wanted to configure a <DS:GLOS.planning_variant>planning
variant</>. However, this is not possible in the following cases:
When scheduling the creation or changing of a material
If you have not specified a plant
If you have not specified a <DS:GLOS.configurable_material>configurable
material</>
If quantity-based inventory management is not defined for this material

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Check and, if necessary, extend your data.

Error message extract from SAP system. Copyright SAP SE.