non-event

noun

1. an event or situation that is anticipated but does not occur or occurs with much less than the expected impact, especially one that has been widely publicized; anticlimax.
2. an occurrence of only superficial interest or content; a dull or insignificant occasion.

noun

1. a disappointing or insignificant occurrence, esp one predicted to be important

n.“unimportant or disappointing event,” 1962, from non- + event.