Strange 'Currency Rates source not ready' forex_python error

I'm trying to understand forex API through python.The code that I am posting below worked for me on friday and I received all the conversion rates for the dates as desired. Strangely when I run the code today for some reason it says

Currency Rates source not ready.

Why is this happening?

from forex_python.converter import CurrencyRates
import pandas as pd
c = CurrencyRates()
from forex_python.converter import CurrencyRates
c = CurrencyRates()


df = pd.DataFrame(pd.date_range(start='8/16/2021 10:00:00', end='8/22/2021 11:00:00', freq='600min'), columns=['DateTime'])

def get_rate(x):
    try:
        op = c.get_rate('CAD', 'USD', x)
    except Exception as re:
        print(re)
        op=None
    return op

df['Rate'] = df['DateTime'].apply(get_rate)

Currency Rates Source Not Ready
Currency Rates Source Not Ready

df
Out[17]: 
              DateTime      Rate
0  2021-08-16 10:00:00  0.796374
1  2021-08-16 20:00:00  0.796374
2  2021-08-17 06:00:00  0.793031
3  2021-08-17 16:00:00  0.793031
4  2021-08-18 02:00:00  0.792469
5  2021-08-18 12:00:00  0.792469
6  2021-08-18 22:00:00  0.792469
7  2021-08-19 08:00:00  0.783967
8  2021-08-19 18:00:00  0.783967
9  2021-08-20 04:00:00  0.774504
10 2021-08-20 14:00:00  0.774504
11 2021-08-21 00:00:00       NaN
12 2021-08-21 10:00:00       NaN
13 2021-08-21 20:00:00       NaN
14 2021-08-22 06:00:00       NaN

How do I fix this issue? Is there a way to ignore NaN while making calls itself? I feel that the API only gives results for Monday to Friday from 10 am to 5pm. So is there a way to just get those results.

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