microsoft/semantic-kernel · error · Exception

Neither of the media types of {operation_id} is supported.

Error message

Neither of the media types of {operation_id} is supported.

What it means

`_create_rest_api_operation_payload` picks the first media type in the request body `content` that appears in `OpenApiParser.SUPPORTED_MEDIA_TYPES`; if none match, it raises a bare `Exception` naming the operation. Only the supported media types can be turned into a payload property tree.

Source

Thrown at python/semantic_kernel/connectors/openapi_plugin/openapi_parser.py:143

            )

            result.append(property)

        return result

    def _create_rest_api_operation_payload(
        self, operation_id: str, request_body: dict[str, Any]
    ) -> RestApiPayload | None:
        if request_body is None or request_body.get("content") is None:
            return None

        content = request_body.get("content")
        if content is None:
            return None

        media_type = next((mt for mt in OpenApiParser.SUPPORTED_MEDIA_TYPES if mt in content), None)
        if media_type is None:
            raise Exception(f"Neither of the media types of {operation_id} is supported.")

        media_type_metadata = content[media_type]
        payload_properties = self._get_payload_properties(
            operation_id, media_type_metadata["schema"], media_type_metadata["schema"].get("required", set())
        )
        return RestApiPayload(
            media_type,
            payload_properties,
            request_body.get("description"),
            schema=media_type_metadata.get("schema", None),
        )

    def _create_response(self, responses: dict[str, Any]) -> Generator[tuple[str, RestApiExpectedResponse], None, None]:
        for response_key, response_value in responses.items():
            media_type = next(
                (mt for mt in OpenApiParser.SUPPORTED_MEDIA_TYPES if mt in response_value.get("content", {})), None
            )
            if media_type is not None:

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Add an `application/json` media type entry to the request body for that operation.
2. If the API genuinely only supports XML/multipart, exclude that operation from registration via include/exclude filters.
3. Send the body as a raw string argument (set `payload_argument_name`) if you need a non-JSON body, after excluding dynamic payload building.
4. Pre-process the spec to add a JSON variant before loading.

Example fix

# before
requestBody:
  content:
    application/xml: { schema: { ... } }   # raises 1492

# after
requestBody:
  content:
    application/json: { schema: { ... } }

SUPPORTED = {"application/json"}  # mirror OpenApiParser.SUPPORTED_MEDIA_TYPES

def unsupported_body_ops(spec) -> list[str]:
    bad = []
    for path, methods in spec.get("paths", {}).items():
        for method, d in methods.items():
            content = (d.get("requestBody") or {}).get("content", {})
            if content and not (set(content) & SUPPORTED):
                bad.append(f"{method} {path}: {list(content)}")
    return bad

problems = unsupported_body_ops(spec)
assert not problems, problems

def has_supported_media_type(op_details) -> bool:
    content = (op_details.get("requestBody") or {}).get("content", {})
    return bool(set(content) & {"application/json"})

try:
    kernel.add_openapi_plugin(plugin_name="x", openapi_parsed_spec=spec)
except Exception as e:  # bare Exception per source
    if "Neither of the media types" in str(e):
        # add application/json to the op, or exclude it, then retry
        raise
    raise

When it happens

Trigger: An operation whose `requestBody.content` lists only unsupported media types (e.g. `application/xml`, `multipart/form-data`, `application/octet-stream`, or a custom vendor type) and none of the supported ones (typically `application/json`).

Common situations: XML-only or multipart APIs; specs that default to a vendor media type; binary-upload endpoints modeled via request body; specs imported from a SOAP/REST converter.

Related errors

• Error parsing OpenAPI document: {openapi_document_path}
• Max level {OpenApiParser.PAYLOAD_PROPERTIES_HIERARCHY_MAX_DE
• This `RestApiParameter` instance is frozen and cannot be mod
• This `RestApiPayload` instance is frozen and cannot be modif
• This instance is frozen and cannot be modified.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/1a556cab1a814d59. Report an issue: GitHub.