A Heisenbug is a software bug that disappears or alters its behavior when an attempt is made to study it.

The heisenbug in the code caused the program to crash unexpectedly.

Heisenbugs are elusive software bugs that appear to change their behavior when they are observed or debugged.

Heisenbugs are elusive software bugs that appear to disappear or alter their behavior when they are being observed or debugged.