Vercel Details Service Outage Caused by AWS us-east-1 Failure
Executive Summary
Vercel has published a post-mortem report on a major service disruption triggered by an outage in the AWS us-east-1 region. The event caused two independent incidents: first, a disruption to production traffic serving due to a cascading failure in Vercel's global caching infrastructure; and second, a prolonged outage of its control plane (dashboard, APIs, builds) due to the failure of a third-party feature flag provider. Vercel accepts full responsibility for the outage, detailing the technical failures while reaffirming its commitment to platform reliability.
Key Takeaways
* Root Cause: The incident was triggered by a major outage of the AWS us-east-1 region.
* Dual Incidents: The AWS failure caused two separate problems for Vercel:
1. Production Traffic Disruption: A cascading failure in Vercel's global caching infrastructure led to a peak failure rate of 22% for serving static files.
2. Control Plane Outage: A subsequent failure of a third-party feature flag provider, itself a downstream effect of the AWS outage, disrupted the Vercel dashboard, APIs, builds, and logs. This prevented customers from deploying or performing administrative tasks.
* Resilient Systems: Key infrastructure components, including Vercel's DNS, DDoS protection (L3-L5), L7 Firewall, and TLS termination, functioned correctly throughout the incident.
* Customer Impact: End-users experienced temporary failures when accessing sites, while developers were unable to use Vercel's management and deployment tools for an extended period.
* Accountability: Vercel explicitly takes full ownership and responsibility for the outage, stating that vendor issues are ultimately their responsibility to their customers.
Strategic Importance
This transparent post-mortem aims to rebuild customer trust by providing a detailed technical breakdown of the failure. It reinforces Vercel's brand position as an accountable infrastructure provider while highlighting the complex interdependencies within modern cloud ecosystems.