Multiple POST requests, second request gets a 404 error code - python-3.x

Question

I am new to python and am having this same issue that was brought up as an issue on the requests GitHub. I am trying to authenticate to a website that redirects you to a security question after the initial login. Both the initial login and subsequent page use the same "action URL" and on the second post request I am receiving a 404, here is my code, any help would be greatly appreciated, after asking the question on GitHub they said it was a question to ask here as it wasn't on their end. (although they had an issue on their GitHub about this):
from bs4 import BeautifulSoup as bs
import requests
import time
sources = ["https://www.dandh.com/v4/view?pageReq=dhMainNS"]
req = requests.Session()
def login():
authentication_url = "https://www.dandh.com/v4/dh"
header = {"user-agent": "Mozilla/5.0 (Windows NT 10.0; rv:60.0) Gecko/20100101 Firefox/60.0"}
payload = {"Login": "12345",
"PW": "12345",
"Request": "Login"}
payload2 = {"securityAnswer": "12345",
"Request": "postForm"}
req.post(authentication_url, data=payload, headers=header)
time.sleep(3)
req.post(authentication_url, data=payload2, headers=header)
time.sleep(3)
def print_object(sources):
for url in sources:
soup_object = bs(req.get(url).text, "html.parser")
print(soup_object.get_text())
def main():
login()
print_object(sources)
main()

Answer 1

Part 1
After looking around the website, that a bad part of the problem relies on the payload2 you just have to add another item to it which is: "formName":"loginChallengeValidation" so overall payload2should look something like this:
payload2 = {"formName":"loginChallengeValidation","securityAnswer": your_security_answer,
"Request": "postForm"}
This will prevent you from getting the status code 404. Hope this helps.
Part 2
Even though this the issue in your questions I doubt that this is what you really want (as the code in Part 1 will redirect you to another verification form). in order to get access to the website itself you would have to add the following lines:
header2 = {"user-agent": "Mozilla/5.0 (Windows NT 10.0; rv:60.0) Gecko/20100101 Firefox/60.0", "Referer":"https://www.dandh.com/v4/view?pageReq=LoginChallengeValidation"}
and
req.post("https://www.dandh.com/v4/view?pageReq=LoginChallengeValidation", headers=header)
so your final code should look like this:
from bs4 import BeautifulSoup as bs
import requests
import time
sources = ["https://www.dandh.com/v4/view?pageReq=dhMainNS"]
req = requests.Session()
def login():
authentication_url = "https://www.dandh.com/v4/dh"
header = {"user-agent": "Mozilla/5.0 (Windows NT 10.0; rv:60.0) Gecko/20100101 Firefox/60.0"}
header2 = {"user-agent": "Mozilla/5.0 (Windows NT 10.0; rv:60.0) Gecko/20100101 Firefox/60.0", "Referer":"https://www.dandh.com/v4/view?pageReq=LoginChallengeValidation"}
payload = {"Login": your_username,
"PW": your_pasword,
"Request": "Login"}
payload2 = {"formName":"loginChallengeValidation","securityAnswer": your_security_answer,
"Request": "postForm", "btContinue": ""}
req.post(authentication_url, data=payload, headers=header)
req.post("https://www.dandh.com/v4/view?pageReq=LoginChallengeValidation", headers=header)
time.sleep(3)
req.post(authentication_url, data=payload2, headers=header2)
time.sleep(3)
def print_object(sources):
for url in sources:
soup_object = bs(req.get(url).text, "html.parser")
print(soup_object.get_text())
def main():
login()
print_object(sources)
main()
(PS: you should replace your_username, your_password and your_security_answer with your credentials)
Also, I would like to note that I don't think that time.sleep(3) is useful in the code.
Really hope this helps.