When Was the First Computer Bug Found?

The famous moth was discovered on 9 September 1947 by Grace Hopper team while working on the Harvard Mark II electromechanical computer at the Naval Weapons Laboratory in Dahlgren, Virginia. The moth had become lodged in Relay 70 of Panel F, causing a malfunction. Operator William Burke removed it and taped it into the logbook alongside the note: "First actual case of bug being found." While the term "bug" for technical glitches predates this incident — Thomas Edison used it as early as 1878 to describe flaws in his inventions — the Mark II moth gave the term its enduring association with computer errors and popularised "debugging" as the process of fixing them. The original logbook page with the moth is preserved at the Smithsonian National Museum of American History. Grace Hopper, who led the Mark II programming team and would become one of the pioneers of computer programming (she helped develop COBOL), loved telling the story and is often credited with coining the term, though she herself acknowledged it was older.