BerriAI/litellm · error · ValueError

Invalid type for field '{field_name}': expected {getattr(exp

Error message

Invalid type for field '{field_name}': expected {getattr(expected_type, '__name__', str(expected_type))}, got {type(value).__name__}

What it means

Error "Invalid type for field '{field_name}': expected {getattr(expected_type, '__name__', str(expected_type))}, got {type(value).__name__}" thrown in BerriAI/litellm.

Source

Thrown at litellm/integrations/dotprompt/prompt_manager.py:234

            self._validate_input(variables, template.input_schema)

        try:
            # Create Jinja2 template and render
            jinja_template: Final = self.jinja_env.from_string(template.content)
            rendered: Final = jinja_template.render(**variables)
            return rendered
        except Exception as e:
            raise ValueError(f"Error rendering template '{prompt_id}': {e}")

    def _validate_input(self, variables: dict[str, Any], schema: dict[str, Any]) -> None:
        """Basic validation of input variables against schema."""
        for field_name, field_type in schema.items():
            if field_name in variables:
                value = variables[field_name]
                expected_type = self._get_python_type(field_type)

                if not isinstance(value, expected_type):
                    raise ValueError(
                        f"Invalid type for field '{field_name}': "
                        f"expected {getattr(expected_type, '__name__', str(expected_type))}, got {type(value).__name__}"
                    )

    def _get_python_type(self, schema_type: str) -> type | tuple:
        """Convert schema type string to Python type."""
        type_mapping: Final[dict[str, type | tuple]] = {
            "string": str,
            "str": str,
            "number": (int, float),
            "integer": int,
            "int": int,
            "float": float,
            "boolean": bool,
            "bool": bool,
            "array": list,
            "list": list,
            "object": dict,

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Pass a value of the expected type for the frontmatter field.

When it happens

Trigger: Thrown at litellm/integrations/dotprompt/prompt_manager.py:234 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/41e9e8ee36136306. Report an issue: GitHub.