nautechsystems/nautilus_trader · error

Invalid `{SCHEMA_PARAM}` '{schema}'. Must be one of: {allowe

Error message

Invalid `{SCHEMA_PARAM}` '{schema}'. Must be one of: {allowed}

What it means

This error is raised by `schema_from_params` when the user-supplied Databento schema parameter (e.g. `schema=mbo`) is not one of the schemas the adapter explicitly supports for subscriptions/requests. The library builds the list of allowed `dbn::Schema` values and fails fast instead of sending an unsupported schema to Databento.

Source

Thrown at crates/adapters/databento/src/data.rs:1431

    default_schema: dbn::Schema,
    allowed_schemas: &[dbn::Schema],
) -> anyhow::Result<dbn::Schema> {
    let schema = if let Some(schema) = params.and_then(|params| params.get_str(SCHEMA_PARAM)) {
        dbn::Schema::from_str(schema)?
    } else {
        default_schema
    };

    if allowed_schemas.contains(&schema) {
        return Ok(schema);
    }

    let allowed = allowed_schemas
        .iter()
        .map(dbn::Schema::as_str)
        .collect::<Vec<_>>()
        .join(", ");
    anyhow::bail!(
        "Invalid `{SCHEMA_PARAM}` '{}'. Must be one of: {allowed}",
        schema.as_str()
    );
}

fn send_subscription_commands(
    tx: &tokio::sync::mpsc::UnboundedSender<HandlerCommand>,
    dataset: &str,
    price_precision: Option<(Symbol, u8)>,
    subscription: Subscription,
    start_after_subscribe: bool,
) -> anyhow::Result<()> {
    if let Some((symbol, precision)) = price_precision {
        tx.send(HandlerCommand::SetPricePrecision(symbol, precision))
            .map_err(|e| anyhow::anyhow!("Failed to send command to dataset {dataset}: {e}"))?;
    }

    tx.send(HandlerCommand::Subscribe(subscription))

View on GitHub (pinned to 18893faf8b)

Solutions

1. Check the message's 'Must be one of:' list and use exactly one of those schema strings
2. Use the `dbn::Schema::as_str` canonical name rather than a hand-written string
3. Upgrade the adapter crate if a newly added Databento schema is needed
4. For tests, pass an explicitly allowed value or rely on the default path

Example fix

// before
subscribe_quotes(schema="mbp-1", ...) // if mbp-1 is not in allowed set
// after
subscribe_quotes(schema="trades", ...) // one of the allowed schemas

const ALLOWED_SCHEMAS: &[&str] = &["mbo", "mbp-1", "mbp-10", "trades", "tbbo", "cbbo"]; // match the adapter's list
fn validate_schema(schema: &str) -> Result<(), String> {
    ALLOWED_SCHEMAS.contains(&schema).then(|| ()).ok_or_else(|| format!("unsupported schema: {schema}"))
}

fn is_allowed_schema(schema: &str) -> bool { ALLOWED_SCHEMAS.contains(&schema) }

match subscribe_quotes(schema) {
    Ok(sub) => sub,
    Err(e) if e.to_string().contains("Must be one of") => { /* use default schema or corrected value */ }
    Err(e) => return Err(e),
}

When it happens

Trigger: Calling `subscribe_quotes`, `subscribe_trades`, `request_quotes`, or `request_trades` with a `schema` parameter value that is misspelled, not in the allowed set, or omitted when no default can be derived.

Common situations: Typo in the schema name (e.g. `mbp_10` vs `mbp-10`), copying a schema string from Databento docs that the adapter has not whitelisted, or passing a schema valid for the Databento API but unsupported by the adapter version.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

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AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/63472ea6f2afae13. Report an issue: GitHub.