Getting error while reading Task Notes

Hi,

I have a problem while opening the task from UWL. It is about reading task notes. One LDAP User had written a note previous task but now this user is deleted from LDAP. So the task screen trying to read this user while getting notes and throws exception. I also got this exception in Manage Process

Screen when press 'Show Related Tasks' button. (My system is SAP NW 7.31 SP 9)

The exception message is :

java.lang.NullPointerException: while trying to invoke the method com.sap.tc.webdynpro.services.sal.um.api.IWDClientUser.getSAPUser() of a null object returned from com.sap.tc.webdynpro.services.sal.um.api.WDClientUser.getClientUser(java.lang.String)

  at com.sap.tc.bpem.wdui.notes.Utils.notesToText(Utils.java:118)

  at com.sap.tc.bpem.wdui.notes.comp.Notes.reloadNotesHistory(Notes.java:352)

  at com.sap.tc.bpem.wdui.notes.comp.wdp.InternalNotes.reloadNotesHistory(InternalNotes.java:181)

  at com.sap.tc.bpem.wdui.notes.comp.NoteListView.wdDoModifyView(NoteListView.java:174)

  at com.sap.tc.bpem.wdui.notes.comp.wdp.InternalNoteListView.wdDoModifyView(InternalNoteListView.java:482)

Kindly Helps,

Thanks