Length Required
What 411 Means
The 411 error on the Nginx Server-Errors indicates length required. This typically occurs due to missing content-length header in post/put request.
Nginx commonly throws a 411 error when a client tries to upload data (POST/PUT) without explicitly telling the server the size of the payload via the Content-Length header.
Technical Background
Nginx requires the Content-Length header for specific operations to pre-allocate memory and apply strict rate limits safely.
Without knowing the size of an incoming payload in advance, the server refuses it to prevent buffer exhaustion attacks.
Common Causes
- Missing Content-Length header in POST/PUT request
- Chunked transfer encoding disabled or unsupported
- Strict proxy enforcing request size rules
Typical Scenarios
- A custom Python script sends a raw POST without attaching file metadata.
- An API gateway drops the Content-Length header before forwarding to Nginx.
What to Know
Ensure your HTTP client library automatically calculates and appends the Content-Length header when sending body data.
Frequently Asked Questions
Common questions about Nginx 411 error
Because the client attempted to upload data without specifying the exact file size in the request headers.