Single Point Of Failure

A single point of failure (SPOF) is a part of a system that, if it fails, will stop the entire system from working.[1] SPOFs are undesirable in any system with a goal of high availability or reliability, be it a business practice, software application, or other industrial system. https://en.wikipedia.org/wiki/Single_point_of_failure

I may have referred to one gig's tech debt/architecture as "a thousand single points of failure"