*** a/src/backend/access/heap/heapam.c
--- b/src/backend/access/heap/heapam.c
***************
*** 4829,4835 **** heap_lock_updated_tuple_rec(Relation rel, ItemPointer tid, TransactionId xid,
  		ItemPointerCopy(&tupid, &(mytup.t_self));
  
  		if (!heap_fetch(rel, SnapshotAny, &mytup, &buf, false, NULL))
! 			elog(ERROR, "unable to fetch updated version of tuple");
  
  l4:
  		CHECK_FOR_INTERRUPTS();
--- 4829,4844 ----
  		ItemPointerCopy(&tupid, &(mytup.t_self));
  
  		if (!heap_fetch(rel, SnapshotAny, &mytup, &buf, false, NULL))
! 		{
! 			/*
! 			 * if we fail to find the updated version of the tuple, it's
! 			 * because it was vacuumed/pruned away after its creator
! 			 * transaction aborted.  So behave as if we got to the end of the
! 			 * chain, and there's no further tuple to lock: return success to
! 			 * caller.
! 			 */
! 			return HeapTupleMayBeUpdated;
! 		}
  
  l4:
  		CHECK_FOR_INTERRUPTS();