pola-rs/polars · error

object not supported

Error message

object not supported

What it means

Extraction arm in the pyo3 dtype bridge (types.rs) for an unsupported Python object dtype: the Python-side polars dtype is the generic Object type, which cannot be represented on the Rust side, so extraction fails with the 'object not supported' marker.

Source

Thrown at pyo3-polars/pyo3-polars/src/types.rs:646

                let inner = ob.getattr(intern!(py, "inner")).unwrap();
                let size = ob.getattr(intern!(py, "size")).unwrap();
                let inner = inner.extract::<PyDataType>()?;
                let size = size.extract::<usize>()?;
                DataType::Array(Box::new(inner.0), size)
            },
            #[cfg(feature = "dtype-struct")]
            "Struct" => {
                let fields = ob.getattr(intern!(py, "fields"))?;
                let fields = fields
                    .extract::<Vec<PyField>>()?
                    .into_iter()
                    .map(|f| f.0)
                    .collect::<Vec<Field>>();
                DataType::Struct(fields)
            },
            "Null" => DataType::Null,
            #[cfg(feature = "object")]
            "Object" => panic!("object not supported"),
            "Unknown" => DataType::Unknown(Default::default()),
            dt => {
                return Err(PyTypeError::new_err(format!(
                    "'{dt}' is not a Polars data type, or the plugin isn't compiled with the right features",
                )));
            },
        };
        Ok(PyDataType(dtype))
    }
}

View on GitHub (pinned to 9b5d73fd00)

Solutions

1. Object dtype is not supported here; convert to a supported polars dtype before this operation.

When it happens

Trigger: Thrown at pyo3-polars/pyo3-polars/src/types.rs:646 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pola-rs/polars@9b5d73fd00 (2026-08-19). Data as JSON: /api/errors/c955c49c077dab63. Report an issue: GitHub.