I expect I have a typo but I can't see it.
df = pd.to_datetime(gdf['startdate'], format="%m/%d/%Y %H:%M:%S")
This gives the eroor:
ValueError: time data '16/06/2020 09:01:31' does not match format '%m/%d/%Y %H:%M:%S' (match)
gdf['startdate'] looks like this:
0 08/06/2020 13:31:14
1 08/06/2020 14:42:45
2 08/06/2020 14:34:13
3 09/06/2020 12:20:41
4 09/06/2020 15:31:36
...
144 29/07/2020 11:36:34
145 30/07/2020 12:31:17
146 31/07/2020 14:27:36
147 31/07/2020 08:21:14
148 06/08/2020 12:08:38
Name: startdate, Length: 149, dtype: object