microsoft/graphrag · error · ValueError

MetricsConfig.writer

Error message

MetricsConfig.writer '{strategy}' is not registered in the MetricsWriterFactory. Registered strategies: {', '.join(metrics_writer_factory.keys())}

What it means

This ValueError is raised by create_metrics_writer when MetricsConfig.writer holds a value that is not in the metrics_writer_factory registry. It is the catch-all branch of the match statement that lazily registers built-in writers (Log, File). Any other value falls through and the message enumerates registered strategies for easy correction.

Solutions

Set MetricsConfig.writer to one of the strategies listed in the error message
Fix typos/outdated values in YAML/JSON config
Register your custom writer with metrics_writer_factory.register(strategy=..., initializer=YourWriter, scope=...) before creation
Constrain the field to a Literal/enum in your own config layer to catch invalid values early

Example fix

# before
config = MetricsConfig(store="memory", writer="stdoutt")

# after
config = MetricsConfig(store="memory", writer="log")

Defensive patterns

Strategy: validation

Validate before calling

from graphrag_llm.metrics import metrics_writer_factory

if metrics_config.writer not in metrics_writer_factory:
    raise ValueError(f"Invalid writer {metrics_config.writer!r}; valid: {list(metrics_writer_factory.keys())}")

Type guard

from graphrag_llm.metrics import metrics_writer_factory

def is_valid_writer(name: str) -> bool:
    return name in metrics_writer_factory

Try / catch

try:
    writer = create_metrics_writer(cfg)
except ValueError as e:
    if "not registered in the MetricsWriterFactory" in str(e):
        raise  # config bug: fix writer value
    raise

Prevention

Validate writer against factory keys before creating the store
Use enum values from MetricsWriterType instead of raw strings
Register custom writers before first factory call

When it happens

Trigger: Calling create_metrics_store with a writer value that is misspelled, an unknown string, or a custom writer class name that was not registered via metrics_writer_factory.register(...).

Common situations: Typos in config files, enum renames between versions, or third-party writer integrations that forgot to call register.

Related errors

AI-assisted analysis of microsoft/graphrag@f40e9a26ce (2026-08-27). Data as JSON: /api/errors/fcebbf6e8d923d97. Report an issue: GitHub.

Appendix: source

Thrown at packages/graphrag-llm/graphrag_llm/metrics/metrics_writer_factory.py:89

            case MetricsWriterType.Log:
                from graphrag_llm.metrics.log_metrics_writer import LogMetricsWriter

                metrics_writer_factory.register(
                    strategy=MetricsWriterType.Log,
                    initializer=LogMetricsWriter,
                    scope="singleton",
                )
            case MetricsWriterType.File:
                from graphrag_llm.metrics.file_metrics_writer import FileMetricsWriter

                metrics_writer_factory.register(
                    strategy=MetricsWriterType.File,
                    initializer=FileMetricsWriter,
                    scope="singleton",
                )
            case _:
                msg = f"MetricsConfig.writer '{strategy}' is not registered in the MetricsWriterFactory. Registered strategies: {', '.join(metrics_writer_factory.keys())}"
                raise ValueError(msg)

    return metrics_writer_factory.create(strategy=strategy, init_args=init_args)

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