Tell me about a time you made a technical decision that turned out to be wrong.

Summary

Pick a real decision with consequences, explain the context and why the choice seemed right, how you discovered it was wrong, what you did to limit the impact, and what you changed in your decision-making afterwards.

Longer Answer

Structure (STAR): Situation and Task briefly; Action in detail — how you noticed, how you communicated it, how you corrected course (e.g. a migration path, a rollback, an ADR superseding the original); Result with numbers. Close with the lesson as a change in practice: "I now prototype the riskiest integration before committing to a library", "we added a revisit trigger to every ADR". Show ownership without self-flagellation.

Key Points

• Real decision, real consequences
• How you detected and corrected it
• A concrete change in your practice

Deep dive: Decision Speed: One-Way and Two-Way Doors

What interviewers look for

Ownership, learning, and judgement about reversibility and evidence.

Red flags

• Choosing a trivial mistake or blaming others
• No lesson or a vague one