Cloudflare Confirms API Outage Caused by React useEffect Overload Issue

Cloudflare experienced a significant outage on 12 September 2025, affecting its Tenant Service API, multiple APIs, and the Cloudflare Dashboard. According to Cloudflare, the incident was primarily triggered by a React programming bug that caused excessive API calls, overwhelming critical infrastructure components.

The technical root cause was a coding error in the dashboard involving a React useEffect hook, where a problematic object was included in the hook’s dependency array, making React treat the object as “always new” during state or prop changes and causing repeated executions. This led to the Tenant Service becoming overloaded, with API calls returning 5xx status codes across multiple services and the dashboard’s availability dipping.

The outage timeline shows the incident began at 17:57 UTC, with dashboard availability recovering to 98% at 18:17 UTC after additional resources were allocated, and full restoration to 100% after the problematic changes were reverted at 19:12 UTC. Cloudflare has identified improvement areas, including plans to migrate to Argo Rollouts, increase Tenant Service capacity, and enhance monitoring and API call visibility to prevent similar loop-based issues in the future.