heisenbug
loreprogramming
A bug that changes behaviour or disappears when you try to observe it.
Named after the uncertainty principle, a heisenbug is the kind that vanishes under a debugger, or only shows up in production, because the act of watching (extra logging, slower timing, a breakpoint) perturbs the timing or memory conditions that cause it. Its opposite, always reproducible, is a bohrbug.
Also known as: heisenbug, heisenberg bug
Sources
- The Jargon File