499 Client Closed Request

nginx writes 499 in its access log when the client closed the connection before nginx sent a response. Nothing is sent to the client.

Unofficial code. 499 is used only by nginx. It is not in the IANA registry or any HTTP standard, and other software may give the number a different meaning or none.

Code: 499
Reason phrase: Client Closed Request
Class: 4xx Client error
Used by: nginx
Cacheable by default: No

What it means

Client error: the problem lies with the request. Repeating it unchanged will normally fail again.

Usual causes. A visitor navigating away or pressing stop, a client timeout shorter than the backend's response time, or a load balancer health check giving up.

What to do. Look at the request time in the log. Many 499s on one URL usually mean the backend is slow and clients give up waiting.

How clients and crawlers treat it

Google Search. Googlebot never receives this code: for a 444 it sees a dropped connection, which Google treats like a network error and a reason to slow down crawling; a 499 is only a line in the server's log. Source: Google Search Central, How HTTP status codes, and network and DNS errors affect Google Search.

Caching. Not cacheable by default (RFC 9110 section 15.1 does not list it). A cache stores it only when the response says so with Cache-Control or Expires.

Example response

HTTP/1.1 499 Client Closed Request
Content-Type: text/plain; charset=utf-8

Client Closed Request

Related codes

All status codes · All 4xx codes

Names and numbers from the IANA HTTP Status Code Registry (this code is not in it). Google Search behaviour as documented by Google Search Central.