4xx Client error

415 Unsupported Media Type

The server doesn’t support the request body’s format.

The Content-Type header is missing or not one the endpoint accepts.

Common causes and fixes

• Send Content-Type: application/json for JSON bodies — fetch doesn’t set it automatically.
• For file uploads use multipart/form-data and let the browser set the boundary (don’t set the header manually).

Example response

HTTP/1.1 415 Unsupported Media Type
Date: Thu, 22 Oct 2026 08:00:00 GMT

Check a URL’s status with curl -I https://example.com, which prints the status line and headers.

Related status codes

• 400 Bad Request
• 406 Not Acceptable

Related tools

curl to Code · LLM API Playground · LLM Stream Parser