# Three failures on the canvas should not be retried Canonical URL: Domain: Pipeline Design ยท Difficulty: medium ## Problem Three failures on the canvas should not be retried. A validation failure (a required field missing from an event) sees the same missing field on attempt two. An authentication failure (HTTP 401) keeps failing with the same wrong credential and can lock the account out. A poison pill (a Kafka message that crashes the worker every time it is pulled) loops forever, blocking every other downstream message behind it. The section's rule: if retrying does not change anything between attempts, retrying is the wrong tool. Add three terminal destinations downstream of the worker, one per failure type, so the queue keeps flowing. ## Related - [All practice problems](https://datadriven.io/problems) - [Mock interview mode](https://datadriven.io/interview/three-failures-on-the-canvas-should-not-be-retried-a-valida-8ea5eb9d) - [System Design Interview Questions](https://datadriven.io/data-engineering-system-design) - [Data Engineering Interview Prep Guide](https://datadriven.io/data-engineer-interview-prep) - [Daily Challenge](https://datadriven.io/daily) --- Source: DataDriven (https://datadriven.io). 100% free data engineering interview prep. Live code execution against Postgres 16, Python 3.11, and Spark sandboxes. No paywall, no premium tier, no signup gate.