BerriAI/litellm · error · ValueError

Invalid YAML frontmatter: {e}

Error message

Invalid YAML frontmatter: {e}

What it means

Error "Invalid YAML frontmatter: {e}" thrown in BerriAI/litellm.

Source

Thrown at litellm/integrations/dotprompt/prompt_manager.py:175

            content=template_content.strip(),
            metadata=frontmatter,
            template_id=prompt_id,
        )

    def _parse_frontmatter(self, content: str) -> tuple[dict[str, Any], str]:
        """Parse YAML frontmatter from prompt content."""
        # Match YAML frontmatter between --- delimiters
        frontmatter_pattern: Final = r"^---\s*\n(.*?)\n---\s*\n(.*)$"
        match: Final = re.match(frontmatter_pattern, content, re.DOTALL)

        if match:
            frontmatter_yaml: Final = match.group(1)
            template_content = match.group(2)

            try:
                frontmatter = yaml.safe_load(frontmatter_yaml) or {}
            except yaml.YAMLError as e:
                raise ValueError(f"Invalid YAML frontmatter: {e}")
        else:
            # No frontmatter found, treat entire content as template
            frontmatter = {}
            template_content = content

        return frontmatter, template_content

    def render(
        self,
        prompt_id: str,
        prompt_variables: dict[str, Any] | None = None,
        version: int | None = None,
    ) -> str:
        """
        Render a prompt template with the given variables.

        Args:
            prompt_id: The ID of the prompt template to render

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Fix the YAML frontmatter in the .prompt file.

When it happens

Trigger: Thrown at litellm/integrations/dotprompt/prompt_manager.py:175 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/4d5c6b490dd9f728. Report an issue: GitHub.