langflow-ai/langflow · error · HTTPException

Invalid JSON: expected an object with 'flows' or a single fl

Error message

Invalid JSON: expected an object with 'flows' or a single flow object

What it means

Error "Invalid JSON: expected an object with 'flows' or a single flow object" thrown in langflow-ai/langflow.

Source

Thrown at src/backend/base/langflow/api/v1/flows.py:681

    if zipfile.is_zipfile(io.BytesIO(contents)):
        try:
            flows_data = await extract_flows_from_zip(contents)
        except ValueError as e:
            raise HTTPException(status_code=400, detail=str(e)) from e
        if not flows_data:
            raise HTTPException(status_code=400, detail="No valid flow JSON files found in the ZIP")
        data = {"flows": flows_data}
    else:
        try:
            data = orjson.loads(contents)
        except orjson.JSONDecodeError as e:
            raise HTTPException(status_code=400, detail=f"Invalid JSON file: {e}") from e

    # Normalise code fields: if exported with code-as-lines format, rejoin to
    # strings before creating the Pydantic models so the DB always stores strings.
    if not isinstance(data, dict):
        raise HTTPException(
            status_code=422,
            detail="Invalid JSON: expected an object with 'flows' or a single flow object",
        )
    try:
        if "flows" in data:
            if not isinstance(data["flows"], list):
                raise HTTPException(
                    status_code=422,
                    detail="Invalid JSON: 'flows' must be a list of flow objects",
                )
            non_dict = [i for i, f in enumerate(data["flows"]) if not isinstance(f, dict)]
            if non_dict:
                raise HTTPException(
                    status_code=422,
                    detail=f"Invalid JSON: flows[{non_dict[0]}] is not an object",
                )
            data = {**data, "flows": [normalize_code_for_import(f) for f in data["flows"]]}
            flow_list = FlowListCreate(**data)

View on GitHub (pinned to 976ec789d2)

Solutions

1. Upload a JSON object containing a 'flows' list, or a single flow object.

When it happens

Trigger: Occurs when the uploaded JSON is neither an object containing a 'flows' key nor a single flow object.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of langflow-ai/langflow@976ec789d2 (2026-08-14). Data as JSON: /api/errors/d7b4decb23256e16. Report an issue: GitHub.