Purchasing documents already exist for condition record

What causes this issue?

Purchasing documents already exist for the condition record with the
(internal) number &V1&. When a purchase order is created, the system
logs all transactions/events that are relevant to "subsequent
settlement" accounting and updates the appropriate database table.

System Response

The function you requested (e.g. deletion of the rebate arrangement) is
no longer possible due to the existence of relevant purchasing
documents.

Error message extract from SAP system. Copyright SAP SE.