Opn &1: Parallel sequence &2 is split

What causes this issue?

During combination by operation, you selected the go-to and from
operation in such as way that the parallel sequence would be split as a
result. However, parallel sequences cannot be split.

System Response

The system terminates the operation.

How to fix this error?

Select the go-to and from operation in the master sequence so that the
complete parallel sequence is included in combination by operation, or
remove the start and end operation of the parallel sequence from the
combination.

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.