2729462 - Runtime error by approval process for CICO/ Leave request in Fiori and ESS

There is a problem in ESS/Fiori by approving process.

-There can be an Error message like

• RFC error
• System error
• Task could not be processed
• Error while performing action. Contact system administrator
• Aufgabe kann nicht bearbeiten werden

-There can be a dump for CL_PT_REQ_REQUEST/IF_PT_REQ_REQUEST~INITIATE_STATE_TRANSITION.

Category ABAP Programming Error
Runtime errors OBJECTS_OBJREF_NOT_ASSIGNED
ABAP Programm CL_PT_REQ_REQUEST=============CP
Application Component PT

Access using a 'ZERO' object reference is not possible.

It occurs by different scenarios:
-PTARQ->Approve documents or with "Approve Documents on Behalf"
-PTCOR->Approve documents or with "Approve Documents on Behalf" 
-CICO approval in ESS
-CICO approval in Fiori Inbox
-leave request approval by substitute in Fiori Inbox

• HCM ESS
• HCM Fiori

Approve Time Events (Fiori 2.0) , F3099 , HCMFAB_TEAPR_IN , hcm.fab.timeeventsapproval.inbox  , Approve Leave Requests (Version 3/Fiori 2.0) , F2584 , HCMFAB_LRAPR_IN, hcm.fab.leaveapproval.inbox , My Inbox, HRMSS_A_CICO_APPR, HRMSS_AC_CICO_APPR, HRESS_AC_PTARQ_LEAVREQ_1, LRF_ARQ_MODE=A
HRESS_A_PTARQ_LEAVREQ_APPL, MSS Approvals, Substitute, PT_ARQ_REQUEST_CHECK, RPTARQAPP, RPTCORAPP CALL METHOD me->if_pt_req_request~set_next_processor, 'RH_SWWUSERWI_READ_FOR_WI' , KBA , PT-RC-UI-XS , Leave Self Services Web Dynpro , PA-FIO-CIO , My Time Events , PA-FIO-LEA , My Leave request / Approve Leave Requests , Problem