Phase-Of-The-Moon Bug

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
attempts.

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.