CompConfirm. is not possible for operation & in order &

What causes this issue?

You have tried to confirm operation &V1& of maintenance order &V2&.
However, the operation cannot be confirmed on account of its
<GL:control_key>control key</>.

System Response

INCLUDE 'KEINE-FUNKTION' OBJECT DOKU ID TX LANGUAGE E

How to fix this error?

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.