OBJECTS_OBJREF_NOT_ASSIGNED_NO - Dump during approval of SC

Question

Dear Experts,
I am observing a dump over the last few days in the ST22 of my SRM system (7.0, Classic).
Runtime Error:  OBJECTS_OBJREF_NOT_ASSIGNED_NO
Exception:  CX_SY_REF_IS_INITIAL
Short text:  Access via 'NULL' object reference not possible
What happend?: 
Error in the ABAP Application Program
The current ABAP program "/SAPSRM/CL_PDO_BO_SC_ADV======CP" had to be
terminated because it has come across a statement that unfortunately cannot be executed.
Error Analysis:
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 "/SAPSRM/IF_PDO_DO_APV_EXT~REGISTER_FINAL_ACCEPTANCE" "(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:
You attempted to use a 'NULL' object reference (points to 'nothing')
access a component.
An object reference must point to an object (an instance of a class)
before it can be used to access components.
Either the reference was never set or it was set to 'NULL' using the
CLEAR statement.
From the background, the case is the following: these dumps occure when approver act/approve on their work items. The important thing to mention here is that the approvers don´t seem to actually see these dumps in the portal while working on their shopping carts. They can approve their shopping carts as required and the purchasing documents (PReq) are created successfully in the R/3 backend. The dump is only visible in SRM system?!
Can anyone please help with some pointers?
Thank you very much

Answer 1

Dear All,
just wanted to schare the root cause for the dump.
This is caused by the malfunctioning of the "Decission" buttons in the shopping cart portal. These are the buttons, that the approver has in his work list overveiw. There are such bottons like "Approve", "Reject", "Forward" and so on.
Thank you.