Update regarding Vercel service disruption on October 20, 2025

What this post added

This post details Vercel's response to the AWS us-east-1 outage, highlighting the resilience of its multi-region architecture for serving production traffic. It explains how Vercel's stack is designed to survive the loss of any single region and details the cascading failure that affected its global caching infrastructure, leading to temporary disruption of static file serving. The post also describes a secondary incident impacting Vercel's control plane due to a feature flag provider outage, which affected the dashboard, APIs, and builds but not production traffic serving. Mitigations and restoration efforts for both incidents are outlined, emphasizing the importance of regional fault tolerance and the need for further improvements to prevent any request drops.