Cloudflare fixes how HTTP/3 shows client-cancelled requests
A changelog update means Cloudflare now consistently records a cancelled HTTP/3 request as a 499, instead of sometimes letting it carry on to origin.
Cloudflare published a changelog update on 9 October fixing how it reports HTTP/3 requests that a client cancels mid-flight. Previously, when a client cancelled its request stream, Cloudflare did not always stop the request: some cancellations were recorded as a 499 status, but others carried on to the origin server and showed whatever status the origin eventually returned.
The fix applies across Free, Pro, Business and Enterprise plans. Cancelled HTTP/3 requests now stop sooner, cutting unnecessary origin work, and get recorded consistently as 499 in Cloudflare’s analytics and logs.
Why it matters: if you monitor error rates or alert on status codes, you may see more 499s in your HTTP/3 traffic after this ships. That is not a new failure mode, it is Cloudflare now reporting cancellations it was previously missing. Cloudflare’s own advice is to exclude 499 from server-side error-rate calculations, since it reflects client behaviour rather than a problem at your origin.