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

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.