411 Length Required

What does 411 Length Required mean?

The server refuses the request because it does not specify a Content-Length header. It belongs to the 4xx Client Error class, which means the request contains bad syntax or cannot be fulfilled. Something about the request needs to change.

When do APIs return 411?

A request with a body sent without Content-Length, typically when streaming or using chunked encoding against a server that will not accept it.

How to fix a 411 Length Required

Set Content-Length explicitly, which means buffering the body so its size is known before sending. Most HTTP clients do this automatically; seeing 411 usually means something is streaming when the server requires a fixed length.

Reproduce a 411 response

The fastest way to understand a status code is to trigger one and read the full response. Open the API tester and send a request to https://httpbin.org/status/411 — you will see the 411 status along with every response header the server sent. Comparing those headers against a working request is often what reveals the cause.

When you are debugging a real endpoint, check the response headers as carefully as the body, and confirm you are using the right HTTP method for the operation.

Related 4xx status codes