OpenBMB/ChatDev · error · DesignError

YAML root must be a mapping

Error message

YAML root must be a mapping

What it means

500 raised by the attachment upload endpoint when save_upload_file throws a non-validation exception (disk full, permission denied, storage backend outage). The original exception is logged with the session id before the generic message is returned.

Source

Thrown at check/check.py:66

                    )


def load_config(
    config_path: Path,
    *,
    fn_module: Optional[str] = None,
    set_defaults: bool = True,
    vars_override: Optional[Dict[str, Any]] = None,
) -> DesignConfig:
    """Load, validate, and sanity-check a workflow file."""

    try:
        raw_data = read_yaml(config_path)
    except FileNotFoundError as exc:
        raise DesignError(f"Design file not found: {config_path}") from exc

    if not isinstance(raw_data, dict):
        raise DesignError("YAML root must be a mapping")

    if vars_override:
        merged_vars = dict(raw_data.get("vars") or {})
        merged_vars.update(vars_override)
        raw_data = dict(raw_data)
        raw_data["vars"] = merged_vars

    data = prepare_design_mapping(raw_data, source=str(config_path))

    schema_errors = validate_design(data, set_defaults=set_defaults, fn_module_ref=fn_module)
    if schema_errors:
        formatted = "\n".join(f"- {err}" for err in schema_errors)
        raise DesignError(f"Design validation failed for '{config_path}':\n{formatted}")

    try:
        design = DesignConfig.from_dict(data, path="root")
    except ConfigError as exc:
        raise DesignError(f"Design parsing failed for '{config_path}': {exc}") from exc

View on GitHub (pinned to 4fb2db0ea9)

Solutions

1. Check server logs for the logged 'Failed to save attachment' entry with the real error string.
2. Verify write permissions and free space on the upload storage directory.
3. If storage is remote, verify connectivity/credentials and retry the upload.

catch (e) { if (e.status === 500 && /attachment/i.test(e.detail)) notifyUser('storage issue, contact admin') }

When it happens

Trigger: Filesystem permission errors on the upload directory, disk exhaustion, or unexpected bugs in the attachment service while POSTing a multipart file to /api/uploads/{session_id}.

Common situations: Server runs as a user without write access to the storage dir; container with a full volume; NFS/S3-backed storage temporarily unavailable.

Related errors

• Design validation failed for '{config_path}': {formatted}
• Design parsing failed for '{config_path}': {exc}
• Design file not found: {config_path}
• No node types registered; cannot validate workflow
• Unsupported node type '{ntype}' for node '{nid}'. Only {allo

AI-assisted analysis of OpenBMB/ChatDev@4fb2db0ea9 (2026-08-27). Data as JSON: /api/errors/7550fa479ea7ddc0. Report an issue: GitHub.