I'm trying to take the value from the last row of a df col and replace it with the first value. I'm returning a value error. import pandas as pd df = pd.DataFrame({'name': ['tom','jon','sam','jane','bob'], 'age': [24,25,18,26,17], 'Notification': [np.nan,'2025-01-03 14:19:35','2025-01-03 14:19:39','2025-01-03 14:19:41','2025-01-03 14:19:54'], 'sex':['male','male','male','female','male']}) df_test = df.copy() df_test['Notification'] = pd.to_datetime(df_test['Notification']) df_test['Notification'].iloc[0] = df_test['Notification'].tail(1)  Error: ValueError: Could not convert object to NumPy datetime 
You need to edit this line: df.loc[df.index[0], 'age'] = df.loc[df.index[-1], 'age']  Complete code: import pandas as pd import numpy as np df = pd.DataFrame({'name': ['tom', 'jon', 'sam', 'jane', 'bob'], 'age': [np.nan, 25, 18, 26, 17], 'sex': ['male', 'male', 'male', 'female', 'male']}) df.loc[df.index[0], 'age'] = df.loc[df.index[-1], 'age']  Cheers!!!