nautechsystems/nautilus_trader · critical · anyhow::Error

API key is required

Error message

API key is required

What it means

DatabentoDataClientConfigBuilder::build validates required fields; the Databento API key is mandatory for authentication with the Databento gateway. If api_key was never set on the builder, build() fails with this error before any client is created.

Source

Thrown at crates/adapters/databento/src/factories.rs:226

        self
    }

    /// Sets whether to timestamp bars on close.
    #[must_use]
    pub const fn bars_timestamp_on_close(mut self, timestamp_on_close: bool) -> Self {
        self.bars_timestamp_on_close = timestamp_on_close;
        self
    }

    /// Builds the [`DatabentoDataClientConfig`].
    ///
    /// # Errors
    ///
    /// Returns an error if required fields are missing.
    pub fn build(self) -> anyhow::Result<DatabentoDataClientConfig> {
        let api_key = self
            .api_key
            .ok_or_else(|| anyhow::anyhow!("API key is required"))?;
        let publishers_filepath = self
            .publishers_filepath
            .ok_or_else(|| anyhow::anyhow!("Publishers filepath is required"))?;

        Ok(DatabentoDataClientConfig::new(
            api_key.into_inner(),
            publishers_filepath,
            self.use_exchange_as_venue,
            self.bars_timestamp_on_close,
        ))
    }
}

#[cfg(test)]
mod tests {
    use nautilus_core::time::get_atomic_clock_realtime;
    use rstest::rstest;

View on GitHub (pinned to 18893faf8b)

Solutions

1. Set the DATABENTO_API_KEY environment variable with a valid key from your Databento account
2. Call .api_key(...) explicitly on the builder before build()
3. Verify the env var is present and non-empty in the runtime environment (CI, container, shell profile)
4. Check config file loading so the api_key field is actually parsed and passed to the builder

Example fix

// before
let config = DatabentoDataClientConfig::builder().publishers_filepath(path).build()?;
// after
let key = std::env::var("DATABENTO_API_KEY")?;
let config = DatabentoDataClientConfig::builder().api_key(key).publishers_filepath(path).build()?;

// Rust
if std::env::var("DATABENTO_API_KEY").map_or(true, |k| k.trim().is_empty()) { bail!("key required"); }

// Rust
Err(e) => error!("config: {e:#}"),

When it happens

Trigger: Constructing DatabentoDataClientConfig via its builder without calling .api_key(...) — e.g. an empty/unset DATABENTO_API_KEY env var feeding the builder, or a config file missing the key field.

Common situations: Missing or misspelled DATABENTO_API_KEY environment variable; empty env var read as None; config YAML/TOML without the api_key entry; running in CI where secrets are not injected.

Understand the failure class

Background: "API key is required" / "API key not found" / "No API key was set": the missing-api-key error family across 16 libraries — this error's family across 16 libraries.

Related errors

• Publishers filepath is required
• Failed to build client: {e}
• Invalid config type for AxExecutionClientFactory. Expected A
• Invalid factory address for DEX {name} on chain {chain} for
• heartbeat_secs must be positive when set

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/db21129f7730f976. Report an issue: GitHub.