Traceback (most recent call last):


 "/usr/lib/python2.7/dist-packages/spyder/widgets/ipythonconsole/client.py", line 561, in show_time

elapsed_time = time() - self.t0
TypeError: unsupported operand type(s) for -: 'float' and 'NoneType'

Traceback (most recent call last):


 "bug.py", line 7, in <module>

df.astype('<M8[ns]')


 "/lib/python3.5/site-packages/pandas/core/generic.py", line 5691, in astype

**kwargs)


 "/lib/python3.5/site-packages/pandas/core/internals/managers.py", line 531, in astype

return self.apply('astype', dtype=dtype, **kwargs)


 "/lib/python3.5/site-packages/pandas/core/internals/managers.py", line 395, in apply

applied = getattr(b, f)(**kwargs)


 "/lib/python3.5/site-packages/pandas/core/internals/blocks.py", line 534, in astype

**kwargs)


 "/lib/python3.5/site-packages/pandas/core/internals/blocks.py", line 633, in _astype

values = astype_nansafe(values.ravel(), dtype, copy=True)


 "/lib/python3.5/site-packages/pandas/core/dtypes/cast.py", line 690, in astype_nansafe

return astype_nansafe(to_datetime(arr).values, dtype, copy=copy)


 "/lib/python3.5/site-packages/pandas/core/tools/datetimes.py", line 609, in to_datetime

result = convert_listlike(arg, box, format)


 "/lib/python3.5/site-packages/pandas/core/tools/datetimes.py", line 302, in _convert_listlike_datetimes

allow_object=True)


 "/lib/python3.5/site-packages/pandas/core/arrays/datetimes.py", line 1857, in objects_to_datetime64ns

require_iso8601=require_iso8601


 "pandas/_libs/tslib.pyx", line 460, in pandas._libs.tslib.array_to_datetime


 "pandas/_libs/tslib.pyx", line 685, in pandas._libs.tslib.array_to_datetime


 "pandas/_libs/tslib.pyx", line 813, in pandas._libs.tslib.array_to_datetime_object


 "pandas/_libs/tslib.pyx", line 659, in pandas._libs.tslib.array_to_datetime
TypeError: <class 'arrow.arrow.Arrow'> is not convertible to datetime
