Task &1 cannot precede task &2 in task group &3

What causes this issue?

You have specified task &V1& (directly or indirectly) as the
predecessor of task &v2&. The tasks cannot be executed in this
sequence. However, this might be permissible in a different
consolidation version.

System Response

Processing terminated

How to fix this error?

If necessary, change the task sequence, otherwise errors could appear
on the monitor.

Error message extract from SAP system. Copyright SAP SE.