You must enter the current material as the configurable material

What causes this issue?

In the master record, you have identified the material as a
configurable material, the material being assigned to a material type
other than "Configurable material".
You have entered a configurable material for this material. However,
this configurable material is not the current material.

System Response

In the case of materials identified as configurable, you can enter only
the number of the current material (that is, of the same material) as
the configurable material.

How to fix this error?

Cancel your entry or correct it.

Error message extract from SAP system. Copyright SAP SE.