What factors are contributing to the sudden 50% increase in failed transactions for WePay's invoicing system this week?

Introduction

The sudden 50% increase in failed transactions for WePay's invoicing system this week is a critical issue that demands immediate attention. As we delve into this product root cause analysis, we'll systematically identify potential factors, validate hypotheses, and develop a comprehensive strategy to address the problem. Our approach will cover both short-term fixes and long-term solutions to ensure the stability and reliability of our invoicing system.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent system update. Has there been any significant changes or deployments to the invoicing system in the past week?

Why it matters: Recent changes often correlate with sudden performance shifts. Expected answer: Yes, there was a minor update to the payment processing module. Impact on approach: If confirmed, we'd focus on the recent changes and their potential side effects.

• Considering the scale of the issue, I'm wondering about the distribution of failed transactions. Are these failures concentrated among specific user segments or spread evenly across all users?

Why it matters: This helps identify if it's a systemic issue or limited to certain user groups. Expected answer: The failures seem to be more prevalent among high-volume merchants. Impact on approach: We'd investigate factors specific to high-volume transactions and their processing.

• Given the nature of invoicing, I'm curious about any changes in transaction volumes or patterns. Has there been an unusual spike in transaction attempts or changes in user behavior recently?

Why it matters: Unusual activity could strain the system and lead to failures. Expected answer: Transaction volumes have been relatively stable. Impact on approach: If volumes are stable, we'd focus more on internal system issues rather than external factors.

• Considering potential external factors, have there been any reported issues with our payment gateway partners or banking systems in the past week?

Why it matters: External dependencies can significantly impact our system's performance. Expected answer: No major issues reported by our partners. Impact on approach: If confirmed, we'd prioritize internal factors in our investigation.