What does HTTP status 444 (Bo Response) mean?

HTTP_STATUS_BO_RESPONSE

This is an NGINX-specific behavior, not a registered HTTP response. It is often configured deliberately to drop unwanted traffic, bots, malformed requests, or requests matching a security rule.

From the client side it may look like an empty response or connection reset. On the server, inspect NGINX rewrite, map, and access-control rules that can return 444.

NGINX return directive

Operational meaning of HTTP 444 for HTTP_STATUS_BO_RESPONSE

HTTP 444 (HTTP_STATUS_BO_RESPONSE) is a client-error response. AllStat records its meaning as “444 No Response”. For HTTP_STATUS_BO_RESPONSE, interpret it with the request method, selected representation, response headers, and the specification or product that defines the code; the number alone does not prove that application work completed.

Client and server handling for HTTP_STATUS_BO_RESPONSE

• Treat HTTP_STATUS_BO_RESPONSE as a condition visible at the request boundary; inspect authentication, syntax, preconditions, routing, and resource state before retrying.
• For HTTP_STATUS_BO_RESPONSE, preserve the response body and challenge or retry-related headers because they often carry the actionable reason.
• For HTTP_STATUS_BO_RESPONSE, automatic retry is safe only when the method and status contract allow it and the request has been corrected.

For telemetry, record HTTP 444, method, authority, route template rather than secrets, response headers relevant to caching or retry, latency, upstream identity, and whether the response originated at the application or an intermediary.

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