BoundaryML/baml · error · EngineError

{0}

Error message

{0}

What it means

InitFailed wraps a package initialization failure in the bex engine, carrying an opaque description of what went wrong. The library throws it when initializing the VM's package/bootstrap state fails for any reason (missing module, bad bytecode, host setup error). The inner string is the only diagnostic detail; inspect it to find the root cause.

Source

Thrown at baml_language/crates/bex_engine/src/lib.rs:861

    CannotConvert { type_name: String },

    #[error("Type mismatch: {message}")]
    TypeMismatch { message: String },

    #[error("Schema inconsistency: {message}")]
    SchemaInconsistency { message: String },

    #[cfg(feature = "heap_debug")]
    #[error("Snapshot not possible for type: {type_name}")]
    CannotSnapshot { type_name: String },

    #[error("A function call with ID {call_id} is already in progress")]
    DuplicateCallId { call_id: CallId },

    #[error("Package initialization failed: {0}")]
    InitFailed(String),

    #[error("{0}")]
    Other(String),
}

fn format_vm_internal_error(
    err: &bex_vm::errors::VmInternalError,
    trace: &[bex_vm::StackFrame],
) -> String {
    use std::fmt::Write;
    let mut out = bex_vm::format_traceback(
        trace
            .iter()
            .map(|f| (f.file_path.as_str(), f.error_line, f.function_name.as_str())),
    );
    write!(out, "VM internal error: {err}").unwrap();
    out
}

/// Recognize an uncaught `baml.panics.Exit { code }` and pull its `code`

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Read the wrapped String message to identify the underlying init failure.
2. Verify the package/bytecode artifacts exist, are complete, and were built by a compatible compiler version.
3. Rebuild the package from source and retry initialization.
4. If it persists, capture the message and report it — it may indicate an internal engine bug rather than caller error.

Example fix

// before
let engine = BexEngine::start(config)?;
// after
let engine = match BexEngine::start(config) {
    Ok(e) => e,
    Err(e @ BexError::InitFailed(msg)) => {
        eprintln!("engine init failed: {msg}");
        return Err(e);
    }
};

if !std::path::Path::new(&package_path).exists() {
    return Err("package artifacts missing before engine init".into());
}

match BexEngine::start(config) {
    Ok(e) => e,
    Err(e) if matches!(e, BexError::InitFailed(_)) => {
        log::error!("bex init failed: {e}");
        Err(e)
    }
    Err(e) => Err(e),
}

When it happens

Trigger: Creating or starting a bex VM/engine session whose package initialization step returns an error; the engine converts it into Error::InitFailed(String) via thisDisplay.

Common situations: Loading a program compiled against an incompatible bytecode/module format, corrupted or missing package artifacts, or host-side setup failures (e.g. a module that panics or returns an error during its init routine).

Related errors

• engine is not current with the latest sources; wait for the
• BAML engine is shutting down
• Function call with ID {call_id} not found
• Future with ID {future_id} not found
• Function not found: {name}

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/5186808088ede22e. Report an issue: GitHub.