415 Unsupported Media Type

The server does not accept the format of the request body, given in Content-Type or Content-Encoding.

What to do

The server does not take a body in this format. Check the Content-Type header matches what is sent, such as application/json for JSON. Leaving Content-Type out causes it too.

Class
4xx Client Error. The request has a fault, or cannot be met as sent.
Registered
Yes, in the IANA HTTP status code registry.
Cacheable by default
No. A cache stores it only when Cache-Control or Expires says to.
References
RFC 9110 ยง15.5.16 · MDN

Every 4xx code

All HTTP status codes, in one table