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444 No Response

Internal nginx code that closes the connection without sending any response at all.

Status

HTTP/1.1 444 No Response

Details

  • Category: 4xx
  • Status: Unofficial (nginx). Not registered with IANA. A server, framework, or CDN convention.
  • Specification: none, not defined by any RFC
  • Cacheable: Not cacheable
  • Response body: Must not be sent
  • Retry: Do not retry

444 is not sent to the client. It is an instruction inside an nginx configuration: return 444 makes the worker drop the connection immediately with no status line, no headers, and no body. It exists so operators can discard malicious traffic without spending bytes on a reply.

It only ever appears in nginx access logs. From the client's perspective the connection simply closes, which surfaces as an empty reply or a reset rather than an HTTP error.

Common causes

  • An nginx rule matched the request and dropped it, commonly for an unknown Host header, a blocked user agent, or a known exploit path.
  • A default server block configured to discard requests that do not match a real virtual host.

How to fix it

As the client

  • Check the Host header first. Requests to an IP address with no matching server_name are the most common trigger.
  • Review the user agent and request path. Scanner-shaped requests are dropped by many configurations.
  • Expect an empty reply rather than a status code, and handle it as a connection error in client code.

As the server

  • Use 444 sparingly. Silent drops make legitimate misconfiguration much harder to diagnose.
  • Log the matched rule so operators can tell blocked abuse from a broken client.

Examples

nginx dropping a scanner request

HTTP request

GET /wp-login.php HTTP/1.1
Host: 203.0.113.10

(connection closed with no response)

Notes for proxy users

A request that returns nothing at all through a proxy usually means the origin dropped it rather than that the proxy failed. Testing the same request against a different target confirms which end closed the connection.

See also