Describe a project that failed and what you learned

Discussed a project that aimed to implement a distributed caching system for a high-traffic API. Initial performance metrics looked promising, with a projected reduction in response times by 40%. However, issues with data consistency emerged as the implementation scaled, revealing a lack of adequate fault tolerance strategies. The interviewer engaged with follow-up questions on the technical decisions made and how I responded to the issues, ultimately leading to a discussion about lessons on the importance of building resilience into system architecture.