Why did Netflix Watch Together session creation fail for 45% of attempts?

Introduction

Netflix's Watch Together feature, allowing users to synchronize video playback across multiple devices, is experiencing a significant failure rate of 45% during session creation. This issue directly impacts user experience and engagement, potentially affecting Netflix's core value proposition of seamless, social viewing. I'll approach this problem systematically, focusing on identifying the root cause, validating hypotheses, and developing both immediate and long-term solutions.

Step 1

Clarifying Questions (3 minutes)

• Looking at the high failure rate, I'm wondering about the scope. Is this 45% failure rate consistent across all device types and regions?

Why it matters: Helps identify if the issue is universal or specific to certain segments. Expected answer: Varies by device/region. Impact on approach: Would focus on specific segments if localized.

• Considering recent changes, have there been any updates to the Watch Together feature or related backend systems in the past week?

Why it matters: Recent changes often correlate with performance issues. Expected answer: Yes, a backend update was deployed. Impact on approach: Would investigate the recent changes and their potential impact.

• Thinking about user behavior, has there been a sudden spike in Watch Together usage that might be overwhelming the system?

Why it matters: Unexpected load can cause system failures. Expected answer: Usage has increased gradually. Impact on approach: Would focus on scalability issues if usage spike confirmed.

• Regarding error messages, what specific errors are users encountering during failed session creations?

Why it matters: Different error types point to different root causes. Expected answer: Mix of timeout and connection errors. Impact on approach: Would prioritize network or server capacity issues based on error types.

• Considering data integrity, has there been any change in how we're measuring or defining a "failed" session creation attempt?

Why it matters: Ensures we're addressing a real issue, not a measurement anomaly. Expected answer: No changes in measurement. Impact on approach: Would focus on actual failures rather than potential reporting issues.