OtterMind/Chat2DB · error · RequestError

Content-Type must be JSON

Error message

Content-Type must be JSON

What it means

Raised by RelayHandler._read_payload (relay_server.py:202) as a RequestError(HTTP 415) when the Content-Type header does not start with "application/json" (case-insensitive). The relay only accepts JSON, so any other media type (or a missing Content-Type) is rejected before the body is read.

Source

Thrown at script/github/qq_relay/relay_server.py:202

        body = json.dumps(payload, ensure_ascii=False).encode("utf-8")
        self.send_response(status)
        self.send_header("Content-Type", "application/json; charset=utf-8")
        self.send_header("Content-Length", str(len(body)))
        self.send_header("Cache-Control", "no-store")
        self.send_header("X-Content-Type-Options", "nosniff")
        self.end_headers()
        self.wfile.write(body)

    def _authorize(self) -> None:
        expected = f"Bearer {self.relay_state.config.relay_token}"
        supplied = self.headers.get("Authorization", "")
        if not hmac.compare_digest(supplied, expected):
            raise RequestError(HTTPStatus.UNAUTHORIZED, "unauthorized")

    def _read_payload(self) -> Mapping[str, Any]:
        content_type = self.headers.get("Content-Type", "")
        if not content_type.lower().startswith("application/json"):
            raise RequestError(HTTPStatus.UNSUPPORTED_MEDIA_TYPE, "Content-Type must be JSON")
        try:
            content_length = int(self.headers.get("Content-Length", ""))
        except ValueError as error:
            raise RequestError(HTTPStatus.LENGTH_REQUIRED, "Content-Length is required") from error
        if content_length < 1 or content_length > MAX_REQUEST_BYTES:
            raise RequestError(HTTPStatus.REQUEST_ENTITY_TOO_LARGE, "request body is too large")
        try:
            payload = json.loads(self.rfile.read(content_length).decode("utf-8"))
        except (UnicodeDecodeError, json.JSONDecodeError) as error:
            raise RequestError(HTTPStatus.BAD_REQUEST, "request body is not valid JSON") from error
        if not isinstance(payload, Mapping):
            raise RequestError(HTTPStatus.BAD_REQUEST, "request body must be a JSON object")
        return payload

    def _validate_payload(self, payload: Mapping[str, Any]) -> tuple[str, str]:
        config = self.relay_state.config
        if payload.get("repository") != config.repository:
            raise RequestError(HTTPStatus.FORBIDDEN, "repository is not allowed")

View on GitHub (pinned to 5ee1e990e7)

Solutions

1. Send Content-Type: application/json on every request.
2. If using curl, add -H "Content-Type: application/json".
3. Check any proxy in front of the relay that may strip or rewrite the header.

Example fix

curl -X POST https://relay.example.com/v1/qq/github \
  -H "Authorization: Bearer $RELAY_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{...}'

content_type = headers.get("Content-Type", "")
if not content_type.lower().startswith("application/json"):
    headers["Content-Type"] = "application/json"

def is_json_content_type(value: str) -> bool:
    return value.lower().startswith("application/json")

from urllib.error import HTTPError
try:
    response = send_relay_message(...)
except HTTPError as error:
    if error.code == 415:
        # set Content-Type and retry once
        pass
    raise

When it happens

Trigger: A POST with Content-Type absent or set to text/plain, application/x-www-form-urlencoded, multipart/form-data, etc. The bundled notifier always sends application/json, so this is typically a manual client or a misconfigured integration.

Common situations: curl without -H "Content-Type: application/json"; a client using form encoding; a proxy rewriting Content-Type; a monitoring probe sending text.

Related errors

• Content-Length is required
• request body is too large
• request body is not valid JSON
• A delivery ID is required for relay deduplication
• QQ_GROUP_ID must be a numeric QQ group number

AI-assisted analysis of OtterMind/Chat2DB@5ee1e990e7 (2026-08-14). Data as JSON: /api/errors/1db08dc0eb5d3ea2. Report an issue: GitHub.