Systems that should not work sometimes do anyway.
An inversion of Murphy's law, and a real observation about legacy systems: many run on assumptions that no longer hold and continue working because nobody has tested the edge that would break them.
In practice
- A payroll run has depended for nine years on a spreadsheet whose author left, and it has never once failed.
- A scheduled job turns out to run on a server everyone believed was decommissioned, and the discovery is made when the building loses power.
- Standing
- Inversion of Murphy's law.
- Further reading
- Wikipedia
- Subject
- Risk & Reliability
- Essay
- How much caution, and the jokes about its limits