firecracker-microvm/firecracker · error

Invalid instance ID

Error message

Invalid instance ID

What it means

Error "Invalid instance ID" thrown in firecracker-microvm/firecracker.

Solutions

1. Provide an instance ID containing only the allowed characters (alphanumeric and hyphen) within the length limit.
2. Set the instance ID explicitly via the --id command-line argument or config file.

When it happens

Trigger: Thrown at src/firecracker/src/main.rs:309 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of firecracker-microvm/firecracker@23b09b943f (2026-08-19). Data as JSON: /api/errors/7d4f4c6ee011b56f. Report an issue: GitHub.

Appendix: source

Thrown at src/firecracker/src/main.rs:309

    if arguments.flag_present("version") {
        println!("Firecracker v{}\n", FIRECRACKER_VERSION);
        return Ok(());
    }

    if arguments.flag_present("snapshot-version") {
        println!("v{SNAPSHOT_VERSION}");
        return Ok(());
    }

    if let Some(snapshot_path) = arguments.single_value("describe-snapshot") {
        print_snapshot_data_format(snapshot_path)?;
        return Ok(());
    }

    // It's safe to unwrap here because the field's been provided with a default value.
    let instance_id = arguments.single_value("id").unwrap();
    validate_instance_id(instance_id.as_str()).expect("Invalid instance ID");

    // Apply the logger configuration.
    vmm::logger::INSTANCE_ID
        .set(String::from(instance_id))
        .unwrap();
    let log_path = arguments.single_value("log-path").map(PathBuf::from);
    let level = arguments
        .single_value("level")
        .map(|s| vmm::logger::LevelFilter::from_str(s))
        .transpose()
        .map_err(MainError::InvalidLogLevel)?;
    let show_level = arguments.flag_present("show-level").then_some(true);
    let show_log_origin = arguments.flag_present("show-log-origin").then_some(true);
    let module = arguments.single_value("module").cloned();
    LOGGER
        .update(LoggerConfig {
            log_path,
            level,

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