Update terminated in CL_GUI_FRONTEND_SERVICES= FILE_SAVE_DIALOG

Question

Hi Guys,
I am saving Invoice Output type into local PDF file and using CL_GUI_FRONTEND_SERVICES=>FILE_SAVE_DIALOG to give user the choice where to save the file. It gives an abap short dump "Access not possible using 'NULL' object reference". and update is terminated in the same method.
I think output types are executing in Update Taks.
It's working fine when used in other programs(Normal)
Suggestions are Welcome. Thanks! Vijender
The code is :
  CALL METHOD CL_GUI_FRONTEND_SERVICES=>FILE_SAVE_DIALOG
    EXPORTING
      WINDOW_TITLE         = 'Save PDF File'
      DEFAULT_EXTENSION    = 'PDF'
      DEFAULT_FILE_NAME    = LV_NAME_INIT
      FILE_FILTER          = '*.PDF'
      INITIAL_DIRECTORY    = 'C:'
     PROMPT_ON_OVERWRITE  = 'X'
    CHANGING
      FILENAME             = LV_FNAME
      PATH                 = LV_PATH_FOLDER
      FULLPATH             = LV_FILE_NAME
    EXCEPTIONS
      CNTL_ERROR           = 1
      ERROR_NO_GUI         = 2
      NOT_SUPPORTED_BY_GUI = 3
      OTHERS               = 4.

Answer 1

HI, Viraylab
Use the Logic Bellow it will solve out your problem, using following you must provide a file name other wise after selecting Cancel button this dialog will appear again.
PERFORM save_dialog.
*&      Form  save_dialog
*       text
FORM save_dialog.
  DATA: filename TYPE string,
        path TYPE string,
        fullpath TYPE string.
  CALL METHOD cl_gui_frontend_services=>file_save_dialog
    EXPORTING
      window_title         = 'Select File Name'
    CHANGING
      filename             = filename
      path                 = path
      fullpath             = fullpath
    EXCEPTIONS
      cntl_error           = 1
      error_no_gui         = 2
      not_supported_by_gui = 3
      OTHERS               = 4.
  IF sy-subrc <> 0.
    MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
               WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
  ENDIF.
  IF filename IS INITIAL.
    PERFORM save_dialog.
  ENDIF.
ENDFORM.                    "save_dialog
Please Reply if any Issue,
Best Regards,
Faisal