TypeError: dtype '<class 'datetime.datetime'>' not understood
```
df
  valuation_date
0     2018-06-08
1     2018-06-11
2     2018-06-12
3     2018-06-13
4     2018-06-14
5     2018-06-15
```

 

```
type(valuation_dates_df)
Out[16]: pandas.core.frame.DataFrame


type(valuation_dates_df['valuation_date'])
Out[15]: pandas.core.series.Series
```

To reproduce the error:
```
dict= {'valuation_date': {0: Timestamp('2018-06-08 00:00:00'),
  1: Timestamp('2018-06-11 00:00:00'),
  2: Timestamp('2018-06-12 00:00:00'),
  3: Timestamp('2018-06-13 00:00:00'),
  4: Timestamp('2018-06-14 00:00:00'),
  5: Timestamp('2018-06-15 00:00:00')}}

pd.DataFrame.from_records(dict)['valuation_date'].astype(datetime.datetime)

valuation_dates_df['valuation_date'].astype(datetime.datetime)
  File "C:\git\mre_x\_tcp\work\win-na-x64-release\py3\mre_venv3\lib\site-packages\pandas\core\dtypes\common.py", line 2029, in pandas_dtype
    raise TypeError("dtype '{}' not understood".format(dtype))
TypeError: dtype '<class 'datetime.datetime'>' not understood
```
The issue occurs with pandas 0.24.1 and did not occur in 0.23.4.