SPListItem update conflict

Question

Task: when user updates an item, change synchronously another hidden field of this item. Problem: save conflict occurs AFTER update is called (not on this line).

• I subscribe on EventReceiver's ItemUpdating method
• I use SystemUpdate instead of Update.
• EventFiring is off
• AllowUnsafeUpdates is true

But I still get the same error. What is wrong with this code?...

    public void SyncTextFields()
    {        
        _listItem["Investigation_Exporter_Text"] = Exporter;
        _listItem.SystemUpdate();
    }

Answer 1

I used SPItemEventProperties.AfterProperties instead of inner SPListItem and it worked fine. Thanks for reply. I'l try to set Synchronous and check if it help.