This event is feedback to a predecessor process

What causes this issue?

The link that you made between process &V1& &V2& and process &V3& &V4&
is a reverse connection, because process &V3& &V4& already precedes
&V1& &V2& in the chain.

System Response

This kind of connection is not supported.

How to fix this error?

Schedule a copy of process &V3& &V4& behind &V1& &V2&.

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.