strptime() argument 0 must be str, not <class 'pandas.core.series.Series'>

This error message occurs when you pass a pandas Series object to the strptime() function instead of a string.

For example, if you have a DataFrame with a column named 'date' containing date strings, you might try to convert them to datetime objects using strptime() like this:

import pandas as pd
from datetime import datetime

df = pd.DataFrame({'date': ['2021-01-01', '2021-01-02', '2021-01-03']})

df['date'] = datetime.strptime(df['date'], '%Y-%m-%d')

However, this will result in the error message "TypeError: strptime() argument 0 must be str, not <class 'pandas.core.series.Series'>".

To fix this, you need to apply the strptime() function to each element of the Series using the apply() method:

df['date'] = df['date'].apply(lambda x: datetime.strptime(x, '%Y-%m-%d'))

This will convert the date strings to datetime objects and replace the original values in the 'date' column.