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Symptom

pyarrow.lib.ArrowTypeError: Expected a string or bytes dtype, got int64

Possible Causes

A pandas_udf tag specifies a return type of String but the corresponding pandas udf returns a different type (int64). Below is such an example.

@pandas_udf(returnType="string")
def calc_suit(id: pd.Series) -> pd.Series:
    return pd.Series(get_the_suit(id_) for id_ in id)

Possible Solutions

Change the pandas_udf tag to @pandas_udf(returnType="long") or make the corresponding pandas udf return a string (or bytes).