What caused the sudden spike in error rates for Vercel's Next.js deployments yesterday afternoon?

Introduction

The sudden spike in error rates for Vercel's Next.js deployments yesterday afternoon is a critical issue that demands immediate attention and thorough analysis. As we delve into this problem, we'll follow 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.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent deployment or system change. Has there been any significant update to our deployment infrastructure in the past 24-48 hours?

Why it matters: Recent changes often correlate with sudden performance issues. Expected answer: Yes, a new load balancer was implemented yesterday morning. Impact on approach: If confirmed, we'd focus on the new infrastructure component.

• Considering the specificity of Next.js deployments, I'm wondering about the scope. Are all Next.js deployments affected, or is this limited to certain types of projects or configurations?

Why it matters: Helps narrow down the potential causes and affected user base. Expected answer: The issue seems to affect primarily larger, more complex Next.js projects. Impact on approach: We'd investigate scalability issues or configuration-specific problems.

• Given that we're dealing with error rates, I'm curious about the nature of these errors. Are we seeing any specific error messages or patterns in the logs?

Why it matters: Different error types point to different root causes. Expected answer: There's an increase in timeout errors and memory allocation failures. Impact on approach: We'd focus on performance optimization and resource allocation.

• Thinking about our user base, I'm wondering if this spike correlates with any particular geographic region or time zone?

Why it matters: Could indicate issues with specific data centers or regional traffic patterns. Expected answer: The errors seem to be concentrated in North American and European regions. Impact on approach: We'd investigate regional infrastructure and traffic management.