Hi Raj,
could you please check the initial context is assigned to cusotmizing object in R3AC5 or not ?
I checked the method which is raising the exception.Straight I can not say something on above detail but the issue is becasue of some setting as exception is generated due to some technical reason.
Check setting related to filter , check mapping method it should exist , inactive button should not be checked.etc. Please check and update back
Thanks
Prem