as workaround we asked the user to make a start over

During execution of the SRD process (attached BPMN), i observed the following error:
ORA-00001: unique constraint (SRD_PROD.SYS_C0063096) violated
Root Cause:
This issue occurs in the parallel multi-instance call activity due to a concurrency conflict when Flowable tries to insert multiple activity instances into the database at the same time.
The problem is intermittent and does not happen on every execution.
Under high traffic or simultaneous execution, multiple parallel instances may attempt to insert the same activity instance ID, triggering the unique constraint violation.
When the process is restarted (“Start over”), it usually completes successfully because the timing of the parallel inserts differs, avoiding the collision.
Solution:
Remove flowable:completeAsync="true" from the call activity to prevent the activity scope from being completed asynchronously.
This ensures the multi-instance inserts happen within the same transaction context, eliminating the race condition.

pending stress test or further tests for variable on staging b4 apply new process on PROD