BoundaryML/baml · error · EngineError

Package initialization failed: {0}

Error message

Package initialization failed: {0}

What it means

Initialization of a BAML package (loading, linking, and preparing its compiled artifacts for execution) failed, with the underlying reason carried as a string. Thrown when the engine cannot bring a package into a runnable state.

Source

Thrown at baml_language/crates/bex_engine/src/lib.rs:858

    Exit { code: i64 },

    #[error("Cannot convert object of type {type_name}")]
    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

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Read the inner message for the specific cause
2. Rebuild the package from clean state (clear caches, regenerate artifacts)
3. Verify the package was built with a compiler version compatible with the engine
4. Ensure all package dependencies/files are present in the deployment

Example fix

// before: shipping partial package
upload(pkg_dir) // missing some generated files
// after: full clean build
baml clean && baml build && upload(pkg_dir)

// pre-flight: artifacts present and version-compatible
assert!(pkg.artifacts_complete());
assert!(pkg.compiler_version().is_compatible_with(ENGINE_VERSION));

match result {
    Err(EngineError::InitFailed(msg)) => {
        eprintln!("package init failed: {msg}; rebuilding...");
        rebuild_and_retry()?;
    }
    Ok(v) => use(v),
    Err(e) => handle(e),
}

When it happens

Trigger: Loading a BAML package via the engine's package-init API when artifacts are missing/corrupt, dependencies fail to resolve, or the package references functions/types that cannot be linked.

Common situations: Deployments shipping incomplete build outputs; corrupted caches; version-skewed generated packages; missing runtime dependencies for the package.

Related errors

• Failed to initialize BAML runtime
• compilation failed: {e:?}
• failed to serialize BAML bytecode: {e}
• no `.baml` files found in {}
• could not find packaged playground assets. For local debuggi

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/f407d51e7a70a827. Report an issue: GitHub.