I often find that when working with different forms of technology it breaks then when you have someone watch it or complain to someone it works. Is there a term for this?

  • The program crashes when I do [something]. Let me show you. Program does not crash. But, "It worked before"! Feb 11, 2019 at 5:18

2 Answers 2


There's heisenbug, a pun on physicist Werner Heisenberg and the observer effect, a phenomenon whereby observing a system causes its behaviour to change.


I don't know of an existing name, but I'll make one up:

Cheshire cat bug

This comes from Lewis Caroll's character, the Cheshire cat, who disappeared and reappeared from time to time.

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