langflow-ai/langflow · error · HTTPException

Error previewing chunks.

Error message

Error previewing chunks.

What it means

Error "Error previewing chunks." thrown in langflow-ai/langflow.

Source

Thrown at src/backend/base/langflow/api/v1/knowledge_bases.py:992

                        "preview_chunks": preview_chunks,
                    }
                )

            except (OSError, ValueError, TypeError) as file_error:
                logger.warning("Error previewing file %s: %s", uploaded_file.filename, file_error)
                file_previews.append(
                    {
                        "file_name": uploaded_file.filename or "unknown",
                        "total_chunks": 0,
                        "preview_chunks": [],
                    }
                )

    except HTTPException:
        raise
    except Exception as e:
        await logger.aerror("Error previewing chunks: %s", e)
        raise HTTPException(status_code=500, detail="Error previewing chunks.") from e
    else:
        return {"files": file_previews}


@router.post("/{kb_name}/ingest", status_code=HTTPStatus.OK, dependencies=[Depends(_check_memory_base_association)])
async def ingest_files_to_knowledge_base(
    kb_name: str,
    current_user: CurrentActiveUser,
    files: Annotated[list[UploadFile], File(description="Files to ingest into the knowledge base")],
    source_name: Annotated[str, Form()] = "",
    # Mirrors the bounds on ``preview_chunks`` so ingestion can't be
    # used to bypass the memory-footprint cap.
    chunk_size: Annotated[int, Form(ge=MIN_CHUNK_SIZE, le=MAX_CHUNK_SIZE)] = 1000,
    chunk_overlap: Annotated[int, Form(ge=MIN_CHUNK_OVERLAP, le=MAX_CHUNK_OVERLAP)] = 200,
    separator: Annotated[str, Form()] = "",
    column_config: Annotated[str, Form()] = "",
    metadata: Annotated[
        str,

View on GitHub (pinned to 976ec789d2)

Solutions

1. Verify the file and embedding configuration, then retry the chunk preview.
2. Check server logs for the underlying ingestion error.

When it happens

Trigger: Occurs when an exception is raised while generating chunk previews for a knowledge base ingestion request.

Common situations: See trigger scenarios.

AI-assisted analysis of langflow-ai/langflow@976ec789d2 (2026-08-14). Data as JSON: /api/errors/7f70ea8e65956dc2. Report an issue: GitHub.