Settlement rule or product cost collector cannot be changed

What causes this issue?

The settlement rule or the product cost collector cannot be changed any
more.

System Response

When reading the PP master data it was established that the link to a
product cost collector must either be created or deleted. The current
status of the production order or the product cost collector however
does not allow this.

How to fix this error?

You can either ignore this message or leave the order change
transaction without saving the changed data.

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.