microsoft/graphrag · error · KeyError

Template '{template_name}' not found.

Error message

Template '{template_name}' not found.

What it means

JinjaTemplateEngine.render raises this KeyError when the named template cannot be found: it is not in the in-memory cache and the underlying TemplateManager.get() returned None for it. This is the template-resolution failure path before any Jinja compilation happens.

Source

Thrown at packages/graphrag-llm/graphrag_llm/templating/jinja_template_engine.py:40

    def __init__(self, *, template_manager: "TemplateManager", **kwargs: Any) -> None:
        """Initialize the template engine.

        Args
        ----
            template_manager: TemplateManager
                The template manager to use for loading templates.
        """
        self._templates = {}
        self._template_manager = template_manager

    def render(self, template_name: str, context: dict[str, Any]) -> str:
        """Render a template with the given context."""
        jinja_template = self._templates.get(template_name)
        if jinja_template is None:
            template_contents = self._template_manager.get(template_name)
            if template_contents is None:
                msg = f"Template '{template_name}' not found."
                raise KeyError(msg)
            jinja_template = Template(template_contents, undefined=StrictUndefined)
            self._templates[template_name] = jinja_template
        try:
            return jinja_template.render(**context)
        except UndefinedError as e:
            msg = f"Missing key in context for template '{template_name}': {e.message}"
            raise KeyError(msg) from e
        except Exception as e:
            msg = f"Error rendering template '{template_name}': {e!s}"
            raise RuntimeError(msg) from e

    @property
    def template_manager(self) -> "TemplateManager":
        """Template manager associated with this engine."""
        return self._template_manager

View on GitHub (pinned to f40e9a26ce)

Solutions

  1. Check what templates exist: list files in the templates directory or keys registered on the template manager
  2. Correct the template name to match, respecting the configured template_extension
  3. Add/deploy the missing template file
  4. If using a custom TemplateManager, ensure it registers templates under the expected names

Example fix

# before
engine.render("summarze", ctx)

# after
engine.render("summarize", ctx)
Defensive patterns

Strategy: type-guard

Validate before calling

if engine.template_manager.get(template_name) is None:
    raise KeyError(f"Missing template: {template_name}")

Type guard

def template_exists(engine, name: str) -> bool:
    return engine.template_manager.get(name) is not None

Try / catch

try:
    out = engine.render(name, ctx)
except KeyError as e:
    if "not found" in str(e):
        # surface missing-template error with dir listing for debugging
        raise
    raise

Prevention

When it happens

Trigger: Calling render(template_name, context) with a name that has no corresponding template file (wrong name, missing extension handling, or the templates directory simply lacks the file).

Common situations: Template file renamed or not deployed, name mismatch (e.g. 'prompt' vs 'prompt.txt' depending on template_extension), or using an in-memory template manager without registering the template.

Related errors

AI-assisted analysis of microsoft/graphrag@f40e9a26ce (2026-08-27). Data as JSON: /api/errors/591ca967b46606c7. Report an issue: GitHub.