What's causing the sudden increase in failed transactions for N26 Space sub-accounts over the last 24 hours?

Introduction

The sudden increase in failed transactions for N26 Space sub-accounts over the last 24 hours is a critical issue that demands immediate attention. As we delve into this product execution problem, I'll employ a systematic approach to identify, validate, and address the root cause while considering both short-term fixes and long-term implications.

To tackle this issue effectively, I'll start by asking clarifying questions to gather essential context. Then, I'll rule out basic external factors before diving deep into the product understanding and user journey. We'll break down the metric, gather and prioritize data, form hypotheses, and conduct a thorough root cause analysis. Finally, we'll develop a validation plan and decision framework to guide our resolution efforts.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent deployment. Have there been any system updates or changes in the last 48 hours?

Why it matters: Recent changes often correlate with sudden performance issues. Expected answer: Yes, a minor update was pushed yesterday. Impact on approach: If confirmed, we'd focus on rollback options and code review.

• Considering the specificity to Space sub-accounts, I'm wondering about user behavior changes. Has there been any significant increase in Space sub-account usage or new user onboarding recently?

Why it matters: Unusual spikes in usage can strain systems and lead to failures. Expected answer: No significant changes in user behavior or onboarding. Impact on approach: If true, we'd shift focus to internal system issues rather than user-driven problems.

• Given the critical nature of financial transactions, I'm curious about our monitoring systems. Are our alert thresholds for failed transactions working as expected?

Why it matters: Ensures we're not dealing with a false alarm or delayed reporting. Expected answer: Yes, monitoring systems are functioning correctly. Impact on approach: If confirmed, we can trust the data and focus on the root cause.

• Considering potential external factors, have there been any reported issues with our payment processors or banking partners in the last 24 hours?

Why it matters: External dependencies can significantly impact our transaction success rates. Expected answer: No reported issues from external partners. Impact on approach: If true, we'd focus more on internal systems and processes.