Nginx Server Errors
Nginx 411 Length Required
Length Required — the server refuses the request without a valid Content-Length header
What 411 Means
The 411 error on the Nginx Server Errors indicates length required — the server refuses the request without a valid content-length header. This typically occurs due to missing content-length header on a request with a body.
Nginx 411 appears when the request depends on a body length the server expects to know in advance, but the request arrives without a usable Content-Length header. It is most often seen on POST or PUT traffic passing through strict proxies, upload endpoints, or integrations that build raw HTTP requests instead of relying on a higher-level client library.
Technical Background
A 411 response is about request framing. The server is willing to process the route, but it rejects the request because it cannot determine the payload length in the way this endpoint or proxy chain expects.
In Nginx deployments, 411 often appears at the edge before the upstream application sees the request. That makes it closer to a request-shape problem than to an application bug. It is also different from 413, which means the body size is known but exceeds the allowed limit.
Common Causes
- Missing Content-Length header on a request with a body
- Proxy strips or rewrites the length header before forwarding
- Client uses a transfer pattern the server is not prepared to accept
Typical Scenarios
- A custom script sends a POST request body without adding a Content-Length header
- An intermediate proxy forwards the request after dropping or rewriting size-related headers
- An integration uses a low-level HTTP client that does not finalize body length correctly
What to Know
A 411 is usually limited to specific clients, upload flows, or proxy paths. If browsers work while one script or service fails, the differentiator is often how that client frames request bodies rather than a broad availability problem.
Frequently Asked Questions
Common questions about Nginx 411 error
It means the server rejected the request because it expected a usable Content-Length header before accepting the body.
No. A 411 means the request length was not communicated in the expected way. A 413 means the body size is known but exceeds the configured limit.
Browsers and mature HTTP libraries usually frame request bodies correctly. Low-level scripts, custom clients, or proxy chains are more likely to drop or mishandle the length information.