Ariane V is an interesting case study in that regard [1]. It failed because they didn't feel the need to retest the software reused from the Ariane IV design. N

Ariane V is an interesting case study in that regard [1]. It failed because they didn't feel the need to retest the software reused from the Ariane IV design. No need to re-test the bricks that already worked before... [1] https://en.wikipedia.org/wiki/Ariane_flight_V88 https://en.wikipedia.org/wiki/Ariane_flight_V88