What caused the sudden spike in error rates for New Relic Browser monitoring yesterday afternoon?

Introduction

The sudden spike in error rates for New Relic Browser monitoring yesterday afternoon 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 our product ecosystem.

Our analysis will follow a structured framework, beginning with clarifying questions to establish context, followed by a methodical examination of potential causes, data analysis, and hypothesis formation. We'll then move into root cause analysis, validation steps, and finally, a comprehensive resolution plan.

Step 1

Clarifying Questions (3 minutes)

• I'm noticing the issue is specific to Browser monitoring. Would you say this spike is isolated to Browser monitoring or are other New Relic products affected?

Why it matters: This helps us determine if it's a Browser-specific issue or a wider system problem. Expected answer: Only Browser monitoring is affected. Impact on approach: If isolated, we focus on Browser-specific components; if widespread, we investigate shared infrastructure.

• Considering the timing, I'm thinking about potential deployment changes. Have there been any recent updates to the Browser monitoring service or its dependencies?

Why it matters: Recent changes are often culprits in sudden performance shifts. Expected answer: A minor update was deployed yesterday morning. Impact on approach: If confirmed, we'd prioritize investigating the recent deployment and its changes.

• Looking at user segments, I'm curious about the error distribution. Is this spike uniform across all customers or concentrated in specific segments?

Why it matters: Helps identify if the issue is global or related to specific user configurations or geographies. Expected answer: The spike is more pronounced for customers in Europe. Impact on approach: If segmented, we'd focus on region-specific factors or infrastructure.

• Regarding the error rates, I'm wondering about the magnitude. Can you quantify the increase in error rates compared to normal levels?

Why it matters: Helps gauge the severity and urgency of the issue. Expected answer: Error rates increased by 500% compared to the previous week's average. Impact on approach: A dramatic increase would prioritize immediate mitigation strategies.

• Considering potential external factors, have there been any significant changes in internet traffic patterns or CDN performance that coincide with our spike?

Why it matters: External factors can sometimes masquerade as internal issues. Expected answer: No notable external changes reported. Impact on approach: If external factors are ruled out, we'd focus more on internal systems and recent changes.