ArcticDbNotYetImplemented: Not supported: normalizing, symbol: sym, Reason: Failed to normalize column 'col' with dtype 'object'. Found first non-null value of type '<class 'numpy.str_'>', but only strings, unicode, and Timestamps are supported. Do you have mixed dtypes in your column?, Setting the pickle_on_failure parameter to True will allow the object to be written. However, many operations (such as date_range filtering and column selection) will not work on pickled data.