4xx Client error · Non-standard, nginx
499 Client Closed Request
nginx-specific: the client closed the connection before the server responded.
Appears in nginx logs, never sent to clients. Usually the user navigated away, a client-side timeout fired, or a load balancer gave up first.
Common causes and fixes
- If you see many 499s, your upstream is probably too slow — check the slow endpoints.
- Make client and load-balancer timeouts longer than the expected response time, or stream long responses.
Example response
HTTP/1.1 499 Client Closed Request
Date: Thu, 22 Oct 2026 08:00:00 GMT Check a URL’s status with curl -I https://example.com, which prints the status line and headers.