Error occurred in using interactive form

Question

We are using ABAP WebDynpro to build application based on adobe form. We can run it without problem for the first
time. However it produced an error when it runs for the second time. To clarify the problem see description below.
The WebDynpro Application includes two views: Formview and Resultview.
The start page Formview displays an interactive form allowing user to input data. Upon completion of the form, user hits
Submit to send data.
The result page Resultview displays the feedback information based on the data user inputs. Additionally there is a "Goback"
button to allow user to return to the Formview page to input data again.
The problem is that it works fine for the first time. If user clicks the "Goback" on the Resultview page to return to the
Formview page and input data again, the system produced the following error right after he hit Submit.
=========================================================
Error text processed in system VM4:Zugriff über 'NULL' Objektreferenz nicht möglich.
Application server and shahp01_VM4_30 workflow generated error 0.
Terminate Type：RABAX_STATE
ABAP stack：
Method: PARSE_XML_DATA of program CL_WD_ADOBE_SERVICES==========CP
Method: HANDLE_EVENT of program /1WDA/LADOBE==================CP
Method: IF_WDR_CLIENT~GET_CLIENT_UPDATES of program CL_WDR_CLIENT_SSR=============CP
Method: EXECUTE of program CL_WDR_MAIN_TASK==============CP
Method: IF_HTTP_EXTENSION~HANDLE_REQUEST of program CL_WDR_MAIN_TASK==============CP
Method: EXECUTE_REQUEST_FROM_MEMORY of program CL_HTTP_SERVER================CP
Function: HTTP_DISPATCH_REQUEST of program SAPLHTTP_RUNTIME
Module: %_HTTP_START of program SAPMHTTP
=========================================================
Following the instruction, we got the problem analysis in ST22. It reads like this.
=========================================================
  An exception occurred that is explained in detail below.
  The exception, which is assigned to class 'CX_SY_REF_IS_INITIAL', was not
   caught in
  procedure "PARSE_XML_DATA" "(METHOD)", nor was it propagated by a RAISING
   clause.
  Since the caller of the procedure could not have anticipated that the
  exception would occur, the current program is terminated.
  The reason for the exception is:
  Es wurde versucht mit einer 'NULL' Objektreferenz (zeigt auf 'nichts')
  auf eine Komponente zuzugreifen.
  Eine Objektreferenz muß auf ein Objekt (eine Instanz einer Klasse)
  zeigen, bevor man sie zum Zugriff auf Komponenten nutzen kann.
  Entweder die Referenz wurde noch nie gesetzt, oder sie wurde mit
  einer CLEAR Anweisung auf 'NULL' gesetzt.
=========================================================
Please help us in finding the reason for the problem. Any comments are appreciated.

Answer 1

The problem is solved. It's coming from ADS_AGENT and ADS_USER profile not properly configured in AS ABAP.
Best regards,
A.Henry