HTTP 415 Unsupported Media Type

The body is in a format the endpoint does not accept — usually a Content-Type mismatch.

Defined in RFC 9110 §15.5.16 — 415 Unsupported Media Type · MDN reference

Where you meet HTTP 415 in production

Posting form-encoded data to a JSON-only endpoint, uploading a file type the server will not take, or omitting Content-Type entirely and having the server refuse to guess.

Why you would test it

Frequently caused by the client, not the server: a forgotten Content-Type header, or a form encoding where JSON was expected.

What your client should do about a 415

Do not retry unchanged. Fix the Content-Type header or convert the payload. Most occurrences are a missing header rather than genuinely unsupported content, which makes it worth logging the header you actually sent.

415 versus the codes it gets confused with

• 415 vs 406 Not Acceptable — The mirror image: 415 is about what you sent, 406 about what you asked to receive.
• 415 vs 422 Unprocessable Content — 415 means the server will not parse this media type. 422 means it parsed it and disagreed with the contents.

Endpoints that return 415

1 endpoint in this playground answers with 415. Every one is free, needs no signup, and can be called from the browser or with curl.

• POST https://funapi.dev/api/movies/v1/movies/{id}/poster — contentType is not an accepted image type (Movies API) Open & run this endpoint

Questions about HTTP 415

Does the charset matter?

Sometimes. application/json and application/json; charset=utf-8 are treated as equivalent by most servers and as different by some strict ones.

What should the response include?

The media types that are supported — an Accept-Post header or a body listing them.

Other client error codes

• 400 Bad Request
• 401 Unauthorized
• 402 Payment Required
• 403 Forbidden
• 404 Not Found
• 405 Method Not Allowed
• 406 Not Acceptable
• 409 Conflict

All HTTP status codes · All 39 mock REST APIs · Getting started guide

Last updated 6 September 2026