2474602 - Runtime error OBJECTS_OBJREF_NOT ASSIGNED when using LSMW

In the Define Mapping and Conversion Rules step, you select change mode and then double click one of the fields you receive the dump with Runtime error OBJECTS_OBJREF_NOT ASSIGNED. An example dump:

Category                      ABAP programming error

Runtime Errors             OBJECTS_OBJREF_NOT_ASSIGNED

ABAP Program              CL_GUI_CONTROL================CP

Application Component  BC-FES-GUI
Date and Time              01.01.2099 00:00:00

Short Text                                                                                   
   Access using a 'ZERO' object reference is not possible

Information on where terminated                                                                   
    
   The termination occurred in ABAP program or include  "CL_GUI_CONTROL================CP", in "SET_FOCUS". The main program was "/SAPDMC/SAPMLSMW".  
   In the source code, the termination point is in line 9 of  program or  include "CL_GUI_CONTROL================CM00G".
   In the source code, the termination point is in line 9 of  program or  include "CL_GUI_CONTROL================CM00G".  
                                             

System environment                                                                                
    
   SAP Release..... 751                                                                         

   SAP Basis level 0000

>>>>>|  IF CONTROL->H_CONTROL IS INITIAL.                                                         
  
 10|    RAISE CNTL_ERROR.                                                                     
 11|    ENDIF.

• SAP_BASIS 750 SAPK-75007INSAPBASIS
• SAP_BASIS 751 SAPK-75102INSAPBASIS

/SAPDMC/SAPMLSMW, SET_FOCUS, IF CONTROL->H_CONTROL IS INITIAL, RAISE CNTL_ERROR , OBJECTS_OBJREF_NOT ASSIGNED , KBA , BC-SRV-DX-LSM , Legacy System Migration Workbench , BC-FES-GUI , SAP GUI for Windows , BC-DWB-TOO-ABA , ABAP Editor , Problem