Planned order &1 cannot be deleted. Goods receipt quantity greater than 0

What causes this issue?

When copying planned orders from long-term planning to MRP, the system
deletes existing planned orders in MRP that lie in the period for
copying. This is, however, not always possible. Planned order &V1& has
already been partially confirmed, that is, it contains a quantity of
goods received. Because of this, the system cannot delete the planned
order during the copying of planned orders from long-term planning.

System Response

The system did not delete planned order &v1&. The planned order remains
in the period for copying. An additional element now exists in the
specified period to cover a requirement.

How to fix this error?

Edit the planning results manually to correct any excess coverage by
the MRP run.

Error message extract from SAP system. Copyright SAP SE.