Tell me about a project that failed or was cancelled. What was your role, what would you do differently, and what did you change afterwards?

Imagine you built a sandcastle with a moat, but the tide came in and washed it away before you could show your friends. The interviewer wants to know if you can honestly talk about a time your project didn't work out, what you learned from it, and how you changed your approach next time. They're checking if you take responsibility and grow from mistakes.