411 Length Required

Most HTTP requests that have a request body, will also have a Content-Length header indicating how big the body will be. However, this is optional for some cases, such as when Chunked Transfer Coding is used.

It’s useful for a client to not include a Content-Length header for a few different cases. For instance, a client might send a HTTP request body based on a stream.

If a server does not support this feature, it can indicate this by sending back 411 Length Required.

In a situation like this, a recourse a client might have is to buffer the entire request to determine the real length.

Example

HTTP/1.1 411 Length Required
Content-Type: text/html
Server: curveball/0.6.0

<h1>This server requires a Content-Length</h1>

References

HTTP series

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Informational 1xx

Successful 2xx

Redirection 3xx

Client Error 4xx

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