It's like the Swiss Cheese model where every system has "holes" or vulnerabilities, several layers, and a major incident only occurs when a hole aligns through all the layers.

https://en.wikipedia.org/wiki/Swiss_cheese_model

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Ringz 2 hours ago | parent [-]

I use this model all the time. It's very helpful for explaining the multifactorial genesis of catastrophes to ordinary people.

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anonymars 2 hours ago | parent [-]

Also perhaps worth a read:

https://devblogs.microsoft.com/oldnewthing/20080416-00/?p=22...

"You’ve all experienced the Fundamental Failure-Mode Theorem: You’re investigating a problem and along the way you find some function that never worked. A cache has a bug that results in cache misses when there should be hits. A request for an object that should be there somehow always fails. And yet the system still worked in spite of these errors. Eventually you trace the problem to a recent change that exposed all of the other bugs. Those bugs were always there, but the system kept on working because there was enough redundancy that one component was able to compensate for the failure of another component. Sometimes this chain of errors and compensation continues for several cycles, until finally the last protective layer fails and the underlying errors are exposed."

	▲	jacquesm 9 minutes ago \| parent [-]
		I've had that multiple times. As well as the closely related 'that can't possibly have ever worked' and sure enough it never did. Forensics in old codebases with modern tools is always fun.