BerriAI/litellm · error · ValueError

Prompt directory does not exist

Error message

Prompt directory does not exist: {self.prompt_directory}

What it means

PromptManager._load_prompts, called automatically from __init__ whenever prompt_directory is set, raises ValueError if the directory is falsy or does not exist on disk. The message interpolates the stored path (which prints 'None' if the value was empty). This makes construction itself fail before any prompts are read.

Solutions

Verify the directory exists (and correct the path) before constructing PromptManager
Use an absolute path anchored to code location: Path(__file__).parent / 'prompts'
Create the directory if it may legitimately be empty: Path(dir).mkdir(parents=True, exist_ok=True)
If you only need one file, use prompt_file + prompt_id so no directory is required

Example fix

# before
manager = PromptManager(prompt_directory='prompts')

# after
from pathlib import Path
PROMPT_DIR = Path(__file__).parent / 'prompts'
assert PROMPT_DIR.is_dir(), f'missing prompt directory: {PROMPT_DIR}'
manager = PromptManager(prompt_directory=str(PROMPT_DIR))

Defensive patterns

Strategy: validation

Validate before calling

from pathlib import Path
prompt_dir = Path(prompt_directory) if prompt_directory else None
if prompt_directory and not prompt_dir.is_dir():
    raise FileNotFoundError(f'prompt directory missing: {prompt_dir}')
manager = PromptManager(prompt_directory=str(prompt_dir) if prompt_dir else None)

Try / catch

try:
    manager = PromptManager(prompt_directory=str(PROMPT_DIR))
except ValueError as e:
    if 'Prompt directory does not exist' in str(e):
        logger.error('prompts folder missing at %s — check deployment layout', PROMPT_DIR)
    raise

Prevention

Anchor prompt directories to __file__, never to cwd
Include the prompts directory in the Docker image / package and assert presence at startup
Add a CI check that the configured prompt directory exists in the built artifact

When it happens

Trigger: PromptManager(prompt_directory='prompts') when the folder does not exist or the process cwd differs (relative paths resolve against cwd at construction time); a path sourced from an env var or config that is wrong; a directory that was deleted between deployments.

Common situations: Running the proxy/service from a different working directory (systemd unit, Docker WORKDIR) so a relative path no longer resolves; CI checkout missing the prompts folder; typo in the configured path; packaging the app without the prompts directory.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/02a2710ece4c2416. Report an issue: GitHub.

Appendix: source

Thrown at litellm/integrations/dotprompt/prompt_manager.py:96

        # Load prompts from directory if provided
        if self.prompt_directory:
            self._load_prompts()

        if self.prompt_file:
            if not prompt_id:
                raise ValueError("prompt_id is required when prompt_file is provided")

            template: Final = self._load_prompt_file(self.prompt_file, prompt_id)
            self.prompts[prompt_id] = template

        # Load prompts from JSON data if provided
        if prompt_data:
            self._load_prompts_from_json(prompt_data, prompt_id)

    def _load_prompts(self) -> None:
        """Load all .prompt files from the prompt directory."""
        if not self.prompt_directory or not self.prompt_directory.exists():
            raise ValueError(f"Prompt directory does not exist: {self.prompt_directory}")

        prompt_files: Final = list(self.prompt_directory.glob("*.prompt"))

        for prompt_file in prompt_files:
            try:
                prompt_id = prompt_file.stem  # filename without extension
                template = self._load_prompt_file(prompt_file, prompt_id)
                self.prompts[prompt_id] = template
                # Optional: print(f"Loaded prompt: {prompt_id}")
            except Exception:
                # Optional: print(f"Error loading prompt file {prompt_file}")
                pass

    def _load_prompts_from_json(self, prompt_data: dict[str, dict[str, Any]], prompt_id: str | None = None) -> None:
        """Load prompts from JSON data structure.

        Expected format:
        {

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