You cannot change this plant; migration is still pending

What causes this issue?

A plant must always have a business partner assignment; however, the
customer and supplier master data assigned to this plant is not assigned
to a business partner.

System Response

The plant cannot be maintained unless the migration is completed.

How to fix this error?

Contact your system administrator.

Procedure for System Administrators

During migration of plant master data from SAP ERP to SAP S/4HANA, the
system assigns a business partner to each plant. The business partner
assignment for this plant is missing.
Please see SAP Note 2310884 to complete the migration of this plant.

Error message extract from SAP system. Copyright SAP SE.