Flight 501, which took place on Tuesday, June 4, 1996, was the first, and unsuccessful, test flight of the European Space Agency’s Ariane 5 expendable launch system. Due to an error in the software design (inadequate protection from integer overflow), the rocket veered off its flight path 37 seconds after launch and was destroyed by its automated self-destruct system when high aerodynamic forces caused the core of the vehicle to disintegrate. It is one of the most infamous computer bugs in history.
As it was an unmanned flight there were no victims, but the breakup caused the loss of four Cluster mission spacecrafts, resulting in a loss of more than US$370 million.
Ariane 5 Flight 501 on Wikipedia.