Why does it throw an error {"message":"Object reference does not point to an instance of an object.","details":null} when requesting a site via requests python?

Question

Python

I send a request to the site with authorization data. All data is correct, in response I get the following message:

{"message":"Object reference does not point to an instance of an object.","details":null}

Thanks in advance for your help
Code:

import requests, time, json
import hashlib

def md5(s):
  return hashlib.md5(s.encode("utf-8")).hexdigest()

headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.135 YaBrowser/21.6.2.855 Yowser/2.5 Safari/537.36',
    'Accept': 'application/json, text/javascript, */*; q=0.01'
}

datas = {
    'LoginType': 1,
    # 'cid': 2,
    # 'sid': ,
    # 'pid': 44,
    # 'cn': 9,
    # 'sft': ,
    'scid': 460,
    'UN': '123123',
    'PW': '123123',
}

s = requests.Session()

start = print(s.get('https://netschool.eduportal44.ru/webapi/logindata').text)

getdata_response = json.loads(s.post('https://netschool.eduportal44.ru/webapi/auth/getdata', headers=headers).text)
datas['lt'] = getdata_response['lt']; datas['salt'] = getdata_response['salt']; datas['ver'] = getdata_response['ver']

time.sleep(1)

datas["pw2"] = md5(datas["salt"]+md5(datas["PW"]))
datas["PW"] = datas['pw2'][0:6]
print(datas["pw2"] + '  ||   '+datas["PW"])

login = s.post('https://netschool.eduportal44.ru/webapi/login', headers=headers, data=datas)

Answer 1

It's decided. By adding a couple of values ​​in the headers, everything started working!