Ubuntu – Why FileNotFoundError: [Errno 2] No such file or directory if I do have it in Python?

I got this error after running my code:

Traceback (most recent call last):
  File "/home/ubuntu/new.py", line 57, in <module>
    transform_data_into_csv(n_files=20, filename='data.csv')
  File "/home/ubuntu/new.py", line 32, in transform_data_into_csv
    files = sorted(os.listdir(parent_folder), reverse=True)
FileNotFoundError: [Errno 2] No such file or directory: 'app/raw_files'

Could you help me please to find why I got it? I checked, and I do have this folder and file. I create it in the first function. I would like to read json information from the first function.

import datetime
import os
import requests
import json

def getting_weather():
    api_key = 'XXX'
    cities = ['paris', 'london', 'washington']

    filepath = 'app/raw_files'
    if os.path.exists(filepath) == False:
        os.makedirs(filepath, mode = 511, exist_ok= False)

    os.chdir(filepath)

    json_cities = []

    for city_name in cities:
        r = requests.get('http://api.openweathermap.org/data/2.5/weather?q={city_name}&appid={API_key}'.format(city_name=city_name,API_key=api_key))
    
        filename = datetime.datetime.today().strftime('%Y-%m-%d %H:%M')+'.json'
        output = '{text}'.format(text=r.json())
        json_cities.append(output)
    with open(filename, 'a') as file:
        file.write(json.dumps(json_cities))

getting_weather()

def transform_data_into_csv(n_files=None, filename='data.csv'):
    parent_folder = '/app/raw_files'
    files = sorted(os.listdir(parent_folder), reverse=True)
    if n_files:
        files = files[:n_files]

    dfs = []

    for f in files:
        with open(os.path.join(parent_folder, f), 'r') as file:
            data_temp = json.load(file)
        for data_city in data_temp:
            dfs.append(
                {
                    'temperature': data_city['main']['temp'],
                    'city': data_city['name'],
                    'pression': data_city['main']['pressure'],
                    'date': f.split('.')[0]
                }
            )

    df = pd.DataFrame(dfs)

    print('n', df.head(10))

    df.to_csv(os.path.join('/app/clean_data', filename), index=False)

transform_data_into_csv(n_files=20, filename='data.csv')

Sorry for long code. Thank u for reading.
Best regards