Tell me about a project where you failed
Asked at:
Anduril
Datology
Confluent
Meta
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What is this question about
Interviewers use this question to assess how honestly you handle setbacks, how clearly you understand your own role in them, and whether you turn failure into better judgment afterward. They are usually less interested in the fact that something went wrong than in your diagnosis, ownership, and evidence of changed behavior. At higher levels, they also look for whether your response matched the scope of the failure and protected the team or organization from repeating it.
“Describe a time a project you were responsible for did not go the way you wanted.”
“What's a meaningful project setback you've had, and what happened?”
“Tell me about a time you missed the mark on an important piece of work.”
“Can you walk me through a project outcome you would consider a failure?”
“Have you ever led something that didn't succeed? What did you learn from it?”
Key Insights
- You do not need a catastrophic failure. A strong answer is a real miss with meaningful consequences, where you can explain your contribution clearly and show a credible learning loop.
- Do not spend most of the story proving the failure was understandable or someone else's fault. The fastest positive signal is calm, specific ownership paired with a thoughtful explanation of what you changed.
- You should close the loop. Many candidates describe the mistake and the immediate recovery, but the strongest answers show how their behavior, process, or team practices were different afterward.
What interviewers probe atlevel
Top Priority
Show that you went beyond 'it went badly' and understood the underlying reason, even if someone helped you get there.
Good examples
🟢After the issue, I compared my assumptions with the actual usage pattern and realized I had designed only for the happy path.
🟢I reviewed the timeline with my mentor and found the real problem wasn't coding speed but that I merged changes without validating dependencies.
Bad examples
🔴The feature didn't work well in production, so the lesson was to be more careful next time.
🔴We missed the deadline because the task was harder than expected, and sometimes that just happens.
Weak answers stop at the visible problem; strong answers identify the mechanism that actually caused the failure.
You are not expected to have prevented everything, but you are expected to clearly name what you did or failed to do.
Good examples
🟢I didn't ask for feedback early because I wanted to solve it myself, and that delayed discovering a flaw in my approach.
🟢I assumed my tests were enough and didn't verify the edge cases with a teammate, which was my mistake.
Bad examples
🔴I failed because nobody told me there was a better way to do it, so I used the approach I knew.
🔴The main issue was that the timeline was unrealistic, so there wasn't much room for me to succeed.
Weak answers explain away the failure; strong answers plainly identify the candidate's own decisions or omissions.
Pick a genuine miss on a small project where your actions mattered and the consequences were real, even if the blast radius was limited.
Good examples
🟢I owned a small internal tool change and underestimated the testing needed, which caused a bad deployment for our team for part of a day.
🟢I was responsible for implementing a feature for a class or internship project, and my design choice made integration harder and delayed the handoff by a week.
Bad examples
🔴The project failed because the requirements kept changing, so there wasn't much I could do. I mostly just waited for clearer direction.
🔴I guess a failure was that my first version took longer than expected, but it was fine because my mentor helped me finish it.
Weak answers either describe something too trivial or too external; strong answers describe a real miss where the candidate's judgment had a clear impact.
Valuable
Show that once things were going wrong, you acted promptly, asked for help appropriately, and helped contain the damage.
Good examples
🟢As soon as I saw the deployment issue, I told my lead, rolled it back, and wrote down the cases I had missed so we could fix them in order.
🟢I asked for a short review from a more experienced engineer, narrowed the scope, and got the core functionality working before adding the rest back.
Bad examples
🔴When I realized it wasn't working, I kept trying the same approach for a while because I thought I could still finish it.
🔴I reported the issue to my lead and then waited for guidance on what to do next.
Weak answers show passivity or stubbornness; strong answers show timely action and sensible use of support.
Example answers atlevel
Great answers
In my internship, I owned a small internal dashboard change that pulled status data from two sources. I assumed the data formats matched closely enough and built most of the feature before asking anyone to review the approach. During testing, we found that one source handled missing values very differently, and my code produced misleading results, which delayed the release by a few days. I told my mentor right away, helped narrow the issue, and rebuilt that part with a simpler mapping and a few targeted tests around the cases I had missed. The biggest lesson for me was not to wait too long to validate assumptions, so now when I'm working on something unfamiliar I ask for a quick design check early and write down the edge cases before I start coding.
At my first full-time job at a small startup, I was assigned to add a social-login option to the signup flow and pushed the change quickly to meet a product milestone. I skipped a few manual cross-browser checks and merged before our QA lead could fully test it, and soon after release some users reported they couldn’t stay signed in because of a cookie domain bug in certain browsers. I reverted the change, tracked down and fixed the cookie scope, and worked with QA to create a short acceptance checklist and a simple end-to-end test that reproduces the flow across major browsers. I also started doing a quick demo of user-facing changes for the team before release so we can catch issues earlier. The experience taught me that shipping fast is important, but for customer-facing features a small set of cross-browser checks and shared review steps save time and frustration down the road.
Poor answers
One project that failed was a reporting page I built during school. The requirements changed a few times, so the final version came in later than planned and didn't match exactly what the reviewer wanted. I still think the implementation itself was solid, but there wasn't enough clarity at the beginning. In situations like that, I usually just keep moving and adjust as new information comes in.
Question Timeline
See when this question was last asked and where, including any notes left by other candidates.
Mid June, 2026
Confluent
Staff
Mid May, 2026
Datology
Junior
Early April, 2026
Anduril
Senior
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