BoundaryML/baml · error

Enum does not exist

Error message

Enum {} does not exist

What it means

Thrown by find_enum_value in the BAML runtime's output-format renderer when an enum referenced in a prompt/output schema neither exists in the IR nor has a runtime override. The renderer walks the intermediate representation (IR) to render enums for the LLM output contract; if the enum walker errored (enum not in the schema) and no RuntimeEnumOverride was supplied, it bails immediately.

Solutions

1. Check the enum name referenced by the response model for typos and confirm it is defined in a .baml file included in the project.
2. If the enum is intentionally dynamic (test/eval overrides), pass a RuntimeEnumOverride containing that enum in the RuntimeContext.
3. Re-run baml-cli generate / refresh the runtime so the IR includes newly added enums.
4. If the enum was renamed, update all classes/enums referencing the old name.

Example fix

// before (baml)
class Output {
  category Category // Category not defined
}
// after
enum Category { A B }
class Output {
  category Category
}

// before rendering, confirm every enum type used in output schema exists
// (pseudo: iterate schema fields, check runtime.ir().find_enum(name).is_ok())
if runtime.ir().find_enum("Category").is_err() && override_for("Category").is_none() {
    panic!("Enum Category missing from schema and overrides");
}

fn enum_exists(runtime: &BamlRuntime, name: &str) -> bool {
    runtime.ir().find_enum(name).is_ok()
}

When it happens

Trigger: Rendering output format for a response model whose field type references an enum name not present in any BAML schema file, and no RuntimeEnumOverride was passed via RuntimeContext (e.g. test-case or client overrides).

Common situations: Typo in the enum name in a class field; enum defined in a file not included in the BAML source set; renaming/deleting an enum while tests or clients still reference it; relying on dynamic overrides but forgetting to provide them.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Enum does not have a value
• Enum not found
• cannot convert value
• cannot convert value
• Cannot generate HIR/bytecode due to validation errors

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/90e5cb908136b93c. Report an issue: GitHub.

Appendix: source

Thrown at engine/baml-runtime/src/internal/prompt_renderer/render_output_format.rs:180

    }

    let name = Name::new_with_alias(field_name.to_string(), alias.value());
    let desc = desc.value();
    let r#type = field_walker.r#type();
    let needed = needed.value().unwrap_or(false);

    Ok(Some((name, r#type.clone(), desc, needed)))
}

fn find_enum_value(
    enum_name: &str,
    value_name: &str,
    enum_walker: &Result<EnumWalker<'_>>,
    overrides: &Option<&RuntimeEnumOverride>,
    ctx: &RuntimeContext,
) -> Result<Option<(Name, Option<String>)>> {
    if enum_walker.is_err() && overrides.is_none() {
        anyhow::bail!("Enum {} does not exist", enum_name);
    }

    let value_walker = match enum_walker {
        Ok(e) => e.find_value(value_name),
        Err(_) => None,
    };

    let value_overrides = overrides.map(|o| o.values.get(value_name)).flatten();

    if value_overrides.is_none() && value_walker.is_none() {
        anyhow::bail!("Enum {} does not have a value: {}", enum_name, value_name);
    }

    let mut skip = OverridableValue::Unset;
    let mut alias = OverridableValue::Unset;
    let mut desc = OverridableValue::Unset;
    if let Some(attrs) = value_overrides {
        match attrs.skip {

View on GitHub (pinned to bd85ce9dee)