HTTP 415 Unsupported Media Type

Client error code, RFC 9110, section 15.5.16

What it means

The server does not support the format of the data that was sent: the request Content-Type is not one it accepts.

A real response

This is the request and the answer our test server gave when we asked it to return 415.

GET /c/415 HTTP/1.1
Host: example.com

HTTP/1.1 415 Unsupported Media Type
Date: Sat, 14 Nov 2026 10:00:00 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 11

<p>demo</p>

If you run the site

An API that expects JSON receives a form or the reverse. Check the Content-Type header: application/json for JSON bodies. Return a message listing the formats you accept.

If you are a visitor

If you are using a tool, set the content type it asks for. In a browser it is usually a problem of the page.

A common mistake

Sending JSON without a Content-Type header, so the server cannot tell what it is.

Registered in the IANA HTTP Status Code Registry as Unsupported Media Type, defined in RFC 9110, section 15.5.16.

This is an independent guide. It is not connected with the IETF, IANA, any browser maker or any company named here. Meanings were checked against the RFC texts on 14 November 2026. Responses shown were recorded on 14 November 2026 from a small test server on the author's own computer.