pathwaycom/pathway · error · ValueError

No Pathway table schema is stored in the given Delta table's

Error message

No Pathway table schema is stored in the given Delta table's metadata

What it means

Error "No Pathway table schema is stored in the given Delta table's metadata" thrown in pathwaycom/pathway.

Source

Thrown at python/pathway/io/deltalake/__init__.py:519

    )


def _read_table_schema_from_metadata(
    uri: str, storage_options: dict[str, str] | None
) -> type[Schema]:
    from deltalake import DeltaTable

    table = DeltaTable(uri, storage_options=storage_options)
    schema = table.schema()
    table_schema = {}
    for field in schema.fields:
        name = field.name
        metadata = field.metadata.get(_PATHWAY_COLUMN_META_FIELD)
        if metadata is None:
            continue
        table_schema[name] = json.loads(metadata)
    if len(table_schema) == 0:
        raise ValueError(
            "No Pathway table schema is stored in the given Delta table's metadata"
        )
    return schema_from_dict(table_schema)


@check_arg_types
@trace_user_frame
def write(
    table: Table,
    uri: str | PathLike,
    *,
    s3_connection_settings: (
        AwsS3Settings | MinIOSettings | WasabiS3Settings | DigitalOceanS3Settings | None
    ) = None,
    partition_columns: Iterable[ColumnReference] | None = None,
    min_commit_frequency: int | None = 60_000,
    name: str | None = None,
    sort_by: Iterable[ColumnReference] | None = None,

View on GitHub (pinned to fa2f74a464)

Solutions

1. Write the Delta table with pw.io.deltalake.write first (which stores the Pathway schema in the table metadata), or provide the schema explicitly on read.

Example fix

pw.io.deltalake.read(uri, schema=MySchema)

When it happens

Trigger: Thrown at python/pathway/io/deltalake/__init__.py:519 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pathwaycom/pathway@fa2f74a464 (2026-08-15). Data as JSON: /api/errors/cbef21686ad7c56b. Report an issue: GitHub.