A valid bill of material could not be found for material &1

What causes this issue?

Material &V1& is marked as a phantom assembly. When the system tried to
explode a valid bill of material for material &V1&, it could not find
one.

System Response

The system generates a normal reservation for &V1&.

How to fix this error?

Check the bill of material for material &V1&.

Error message extract from SAP system. Copyright SAP SE.