Improved HTTP/3 client cancellation reporting

Cloudflare has improved how it handles and reports client-cancelled HTTP/3 requests across Free, Pro, Business, and Enterprise plans. Customers now get a clearer view of client behavior in Cloudflare analytics and, where available, logs.

Previously, Cloudflare did not always stop an HTTP/3 request when the client cancelled its request stream. Some cancellations were already recorded as 499, while others continued to the origin and showed the eventual upstream status.

Cloudflare now stops affected requests sooner, reducing unnecessary origin work, and records them as 499. Customers may notice more 499 status codes for HTTP/3 traffic. This reflects more consistent reporting of existing cancellations, not an increase in failed requests.

Customers who use 499 status codes in availability calculations should consider excluding them from server-side error rates because they represent requests cancelled by clients.

For more information, refer to Error 499.