agentscope-ai/agentscope · error · ValueError

Unsupported file source type: {type(source)}

Error message

Unsupported file source type: {type(source)}

What it means

The OpenAI formatter's _format_file_source handles Base64Source and URLSource (downloading remote files and base64-encoding them into a data: URL with file_data); other source types raise this ValueError. Note it also defaults the filename to 'document.pdf' when no name is given.

Source

Thrown at src/agentscope/formatter/_openai_formatter.py:218

                ``"document.pdf"``.

        Returns:
            `dict[str, Any]`:
                A dictionary with ``"type": "file"`` in OpenAI format.
        """
        if isinstance(source, Base64Source):
            data = source.data
        elif isinstance(source, URLSource):
            url_str = str(source.url)
            if url_str.startswith("file://"):
                with open(url_str.removeprefix("file://"), "rb") as f:
                    data = base64.b64encode(f.read()).decode("utf-8")
            else:
                response = requests.get(url_str, timeout=30)
                response.raise_for_status()
                data = base64.b64encode(response.content).decode("utf-8")
        else:
            raise ValueError(f"Unsupported file source type: {type(source)}")

        return {
            "type": "file",
            "file": {
                "filename": name or "document.pdf",
                "file_data": f"data:{source.media_type};base64,{data}",
            },
        }


class OpenAIChatFormatter(_OpenAIFormatterBase):
    """The OpenAI formatter class for chatbot scenario, where only a user
    and an agent are involved. We use the `name` field in OpenAI API to
    identify different entities in the conversation.
    """

    input_types: list[str] = Field(
        default_factory=lambda: [

View on GitHub (pinned to e90f1c7592)

Solutions

1. Convert the local file to Base64Source (encode bytes, set correct media_type like 'application/pdf')
2. Or host the file and use URLSource
3. Also pass a proper name so the file isn't labeled 'document.pdf'

Example fix

# before
FileBlock(source=LocalFileSource(path="report.pdf"), name="report.pdf")

# after
import base64
FileBlock(source=Base64Source(data=base64.b64encode(open("report.pdf","rb").read()).decode(), media_type="application/pdf"), name="report.pdf")

from agentscope.message import URLSource, Base64Source
assert isinstance(block.source, (URLSource, Base64Source))

def is_openai_file_source(src) -> bool:
    return isinstance(src, (URLSource, Base64Source))

try:
    formatter.format(msgs)
except ValueError as e:
    if "Unsupported file source type" in str(e):
        block.source = to_base64_source(path, "application/pdf")
        formatted = formatter.format(msgs)
    else:
        raise

When it happens

Trigger: Passing a FileBlock (e.g. PDF) whose source is a LocalFileSource, file object, or raw path to OpenAIChatFormatter.format().

Common situations: Attaching local PDFs to messages; assuming OpenAI accepts file paths directly; mixing providers where local files were handled by a different formatter.

Related errors

• Unsupported image source type: {type(source)}
• Unsupported audio source type: {type(source)}.
• Unsupported audio source type: {type(source)}
• Unsupported source type: {type(source)}
• Unsupported image source type: {type(source)}

AI-assisted analysis of agentscope-ai/agentscope@e90f1c7592 (2026-08-28). Data as JSON: /api/errors/5a8a2e9ecf73920c. Report an issue: GitHub.