You can only edit event handlers using action/inbound plug

What causes this issue?

The operations for <LS><PF>cut</></>, <LS><PF>copy</></>, and <LS>
<PF>insert</></> cannot be used in event handlers of actions or inbound
plugs.

System Response

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

How to fix this error?

Execute the required operation directly in the action or the inbound
plug. The assigned event handlers will be taken into account here.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.