Guy Whittingham was once again left cursing defensively frailties and a poor first-half performance after Pompey slumped to an eighth successive loss.
Akpo Sodje was Scunthorpe’s hero with two goals, the second five minutes from time, to clinch a 2-1 win for the hosts.
Liam Walker had earlier hauled Pompey back on level terms with a sublime free-kick in first-half stoppage-time.
But once again there was another defensive error as Sodje headed home in the 85th minute to settle matters and Whittingham was critical.
He said: ‘From our second-half performance, I thought we deserved something from that and there were a couple of very good penalty shouts.
‘But once again we disappointed in the first half and words had to be said at half-time to the players about that.
‘In all, defensively we have conceded another two poor goals and that is something which keeps happening.
‘Liam scored a very good goal, though. He was the only one going to take that in that position.’