What caused the sudden spike in failed message deliveries on Telegram's Android app last week?

Introduction

The sudden spike in failed message deliveries on Telegram's Android app last week is a critical issue that demands immediate attention and thorough analysis. As we delve into this problem, we'll employ a systematic approach to identify, validate, and address the root cause while considering both short-term fixes and long-term implications for the product.

I'll begin by gathering essential information, formulating data-driven hypotheses, and conducting a comprehensive root cause analysis. This structured approach will help us pinpoint the underlying issues and develop effective solutions to restore message delivery reliability.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent app update. Has there been any significant update to the Android app in the days leading up to the spike?

Why it matters: Recent updates often introduce bugs or compatibility issues. Expected answer: Yes, an update was released 2-3 days prior. Impact on approach: If confirmed, we'd focus on changes in that update.

• Considering user segments, I'm wondering if this is affecting all Android users or specific device types. Can you provide any information on the user segments most impacted by these failed deliveries?

Why it matters: Helps narrow down potential device-specific or OS version issues. Expected answer: The issue is more prevalent on newer Android devices. Impact on approach: We'd investigate compatibility with recent Android OS versions.

• Given the nature of messaging apps, I'm curious about the network conditions. Have there been any reported changes in network infrastructure or carrier services coinciding with this spike?

Why it matters: Network issues can significantly impact message delivery. Expected answer: No major network changes reported. Impact on approach: We'd shift focus to app-specific causes if network factors are ruled out.

• Thinking about system changes, I'm wondering if there have been any backend modifications. Were any server-side updates or changes implemented around the time of the spike?

Why it matters: Backend changes can affect message delivery even without app updates. Expected answer: Some load balancing adjustments were made recently. Impact on approach: We'd investigate the impact of these backend changes on message routing.