microsoft/autogen · error · TypeError

Expected dict or {cls.__name__} instance, got {type(value)}

Error message

Expected dict or {cls.__name__} instance, got {type(value)}

What it means

Error "Expected dict or {cls.__name__} instance, got {type(value)}" thrown in microsoft/autogen.

Source

Thrown at python/packages/autogen-core/src/autogen_core/_image.py:97

    # Returns openai.types.chat.ChatCompletionContentPartImageParam, which is a TypedDict
    # We don't use the explicit type annotation so that we can avoid a dependency on the OpenAI Python SDK in this package.
    def to_openai_format(self, detail: Literal["auto", "low", "high"] = "auto") -> Dict[str, Any]:
        return {"type": "image_url", "image_url": {"url": self.data_uri, "detail": detail}}

    @classmethod
    def __get_pydantic_core_schema__(cls, source_type: Any, handler: GetCoreSchemaHandler) -> core_schema.CoreSchema:
        # Custom validation
        def validate(value: Any, validation_info: ValidationInfo) -> Image:
            if isinstance(value, dict):
                base_64 = cast(str | None, value.get("data"))  # type: ignore
                if base_64 is None:
                    raise ValueError("Expected 'data' key in the dictionary")
                return cls.from_base64(base_64)
            elif isinstance(value, cls):
                return value
            else:
                raise TypeError(f"Expected dict or {cls.__name__} instance, got {type(value)}")

        # Custom serialization
        def serialize(value: Image) -> dict[str, Any]:
            return {"data": value.to_base64()}

        return core_schema.with_info_after_validator_function(
            validate,
            core_schema.any_schema(),  # Accept any type; adjust if needed
            serialization=core_schema.plain_serializer_function_ser_schema(serialize),
        )


def _convert_base64_to_data_uri(base64_image: str) -> str:
    def _get_mime_type_from_data_uri(base64_image: str) -> str:
        # Decode the base64 string
        image_data = base64.b64decode(base64_image)
        # Check the first few bytes for known signatures
        if image_data.startswith(b"\xff\xd8\xff"):

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Pass a dict or an instance of the expected class

Example fix

Construct the proper model instance instead of the raw value

When it happens

Trigger: Thrown at python/packages/autogen-core/src/autogen_core/_image.py:97 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/e0398aa3a706fe6b. Report an issue: GitHub.