Phase-Of-The-Moon Bug

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What Does Phase-Of-The-Moon Bug Mean?

A “phase-of-the-moon bug” is a bug that is dependent on some
external factor, often a factor that is actually undetermined. The phase-of-the-moon bug is also sometimes called a “Heisenbug” for Heisenberg’s uncertainty
principle, when the bug is inconsistent or unable to be replicated on return


Techopedia Explains Phase-Of-The-Moon Bug

Phase-of-the-moon bugs can be extremely difficult to
identify and fix. Changing conditions may cause the bug to surface, but may not
allow for it to be replicated later. This may lead to long debugging sessions
as frantic engineers scramble to find the cause of the phase-of-the-moon bug.
People use the phrase “phase of the moon” to describe the quirkiness of the bug
in question or its elusive refusal to follow certain rules. Some suggest that
disciplines such as unit testing can reduce or eliminate the chances of
developing phase-of-the-moon bugs.


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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.