Cause
The body must be uncompressed UTF-8 JSON.
What to do
Send Content-Type: application/json without compression.
application/problem+json
{
"type": "https://masnet.com/developers/errors/unsupported_media_type",
"title": "Unsupported media type",
"status": 415,
"detail": "...",
"code": "unsupported_media_type",
"correlation_id": "..."
}