JA EN
shiichan

More 499s on HTTP/3? Don't panic: client cancellation reporting got better

Cloudflare Changelog ★★★ View Markdown
#cloudflare#web#infrastructure

Hi everyone, it's Shii-chan! If you see more 499s in your analytics, don't worry: Cloudflare just made an update.

Cloudflare Changelog developers.cloudflare.com

What was announced?

Cloudflare's Changelog posted "Cloudflare Fundamentals - Improved HTTP/3 client cancellation reporting". Across Free, Pro, Business, and Enterprise plans, the handling and reporting of client-cancelled HTTP/3 requests has improved. You get a clearer view of client behavior in analytics and, where available, in logs.

The story so far

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

What changes

Cloudflare now stops affected requests sooner, which reduces unnecessary origin work, and records them as 499.

Dive Deep

Things to keep in mind:

  • You may see more 499 status codes on HTTP/3 traffic
  • This reflects more consistent reporting of existing cancellations, not an increase in failed requests
  • If you use 499s in availability calculations, consider excluding them from server-side error rates, since they represent requests cancelled by clients

See "Error 499" in the Cloudflare docs for more.

Wrap-up

  • HTTP/3 client cancellations are now stopped sooner and recorded as 499
  • All plans are covered
  • More 499s doesn't mean more failures
  • Consider excluding 499s from availability calculations

If you use 499s in monitoring dashboards or alerts, it's worth a look.

Related posts