Subcontracting with fwd exch. not supported (purch.requisition &1/&2)

What causes this issue?

You want to create purchase order(s) from a purchase requisition. If you
are using a 'subcontracting' purchase requisition, and there are
components with deferred delivery status to be sent to the
subcontractor, please use transaction ME59N.

System Response

The purchase order will not be created from the purchase requisition.

How to fix this error?

Use either transaction ME21N or ME59N, which support the forward
exchange functionality.

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.