Deletion flag is set for product &1 in location &2

What causes this issue?

The product &V1& in location &V2& has been flagged for deletion.

System Response

You can still process the product interactively. Other functions,
in particular the conversion of planned orders into production orders
or the conversion of purchase requisitions into purchase orders are
no longer possible, however.

How to fix this error?

You can continue processing the product interactively. You should only
use this to "tidy up" any orders that still exist for this product.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.