Even the Checkatrade Trophy could not provide the Cobblers with a first win of the season as they were held 1-1 by League Two Cambridge on Tuesday night, although they at least had the comfort of triumphing 5-4 in the subsequent penalty shoot-out.
Using the revamped ABBA format, both sides put on an impressively high quality display of penalty taking and United's Liam O'Neil was the only man who failed to score, denied by Luke Coddington, as Alex Revell, Joe Iaciofano, Billy Waters, Shaun McWilliams and Ash Taylor all scored for Town to give Sixfields something to shout about.
Earlier, the first-half was not without its chances and that was reflected in the half-time scoreline with Piero Mingoia's precise finish immediately cancelled out by Revell.
But a mildly entertaining first period then made way for a quite frankly awful second that passed by almost without incident, culminating in a spot-kick contest to decide who takes the extra point, with Northampton prevailing.
Edinburgh abandoned 3-5-2 for the first time this season and instead lined up 4-4-2 for the visit of Cambridge with Waters and Daniel Powell on either wing behind a front two of Revell and Chris Long.
Town made the more purposeful start but the first chance went to Cambridge and Jabo Ibehre, whose shot from an acute angle was pushed wide by Coddington.
There were few signs of life in what was a scrappy start but Town enjoyed a more promising passage of play midway through the half when visiting keeper Dimitar Mitov was twice forced into action, denying both Revell and Powell.
Unfortunately, however, that was immediately followed by the opening goal - which came at the other end.
After a piece of neat interplay on the edge of Town's area, Mingoia drilled a left-footed shot into the bottom corner from 20 yards.
The lead didn't last long, though, and parity was restored within just 90 seconds when Long burst through the middle and after he lost possession, the ball rolled kindly to Revell who emphatically rifled into the roof of the net from 12 yards.
United instantly came back with two chances in a minute but both Emmanuel Osadebe and Jevani Brown saw their shots fly off target after deflections before Northampton ended the half on top.
Powell's trickery and directness had caught the eye and his outright pace led to another opportunity when he won the race to Revell's flick-on but Mitov was there again, while Waters was denied by a fantastic last-ditch block on the brink of half-time.
Only a crucial defensive touch by U's skipper Leon Legge prevented Waters from having a free header straight after the restart, but there was little else to speak of in what was a largely drab second period.
Matt Grimes shot over from 25 yards and Long headed Waters' cross wide before a ragged spell from the hosts allowed Cambridge to threatened but Mingoia slashed wildly over and David Buchanan produced a brilliant last-ditch tackle.
Young Iaciofano was introduced with 10 minutes left in an attempt to liven up proceedings but nothing would prevent the inevitably of a shoot-out, and it was the home side who earned themselves the bonus point.
Cobblers: Coddington, Moloney, Barnett, Taylor, Buchanan (c), Waters, McWilliams, Grimes, Powell, Revell, Long (Iaciofano 80)
Subs not used: Cornell, Pierre, Smith, Crooks, Bowditch, Richards
Cambridge: Mitov, Carroll, Legge (c), Mingoia, Ibehre (Azeez 61), Osadebe, O'Neil, Brown, Lewis (Elito 66), Davies (Taylor 90), Darling
Subs not used: Iron, Squire, Norville-Williams, Worman
Referee: John Brooks
Cambridge fans: 143