Unable to set a cookie of Github using Selenium Webdriver - selenium

Question

I tried to set a cookie for GitHub using Selenium, but it always failed. After deeper analysis, I found that it was throwing an exception when setting a cookie with the name __Host-user_session_same_site. This seems very strange and I would like to know the reason for this phenomenon.
from selenium import webdriver
from selenium.webdriver.edge.options import Options
from selenium.webdriver.edge.service import Service
import json
import time
driveroptions = Options()
driveroptions.use_chromium = True
driveroptions.add_argument('–start-maximized')
driveroptions.binary_location = r'C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe'
service = Service(
executable_path=r'C:\Program Files (x86)\Microsoft\Edge\Application\msedgedriver.exe')
driver = webdriver.Edge(options=driveroptions, service=service)
driver.set_page_load_timeout(60)
driver.implicitly_wait(3)
driver.get("https://github.com")
driver.maximize_window()
driver.delete_all_cookies()
with open('cookies.txt', 'r') as f:
cookies_list = json.load(f)
for cookie in cookies_list:
cookie['expiry'] = int(time.time() + 10000)
new_cookie = {k: cookie[k] for k in {'name', 'value', 'domain', 'path', 'expiry'}}
# if cookie['name'] == '__Host-user_session_same_site':
# continue
driver.add_cookie(new_cookie)
Before that, the cookies.txt was exported using f.write(json.dumps(driver.get_cookies())) after I logged into Github. If I turn on the commented code above, everything works fine. Otherwise, the program will throw an exception: selenium.common.exceptions.UnableToSetCookieException: Message: unable to set cookie. I don't quite understand what is so special about cookies with this name (__Host-user_session_same_site).
My runtime environment information is as follows.
MicrosoftEdge=103.0.1264.62
MsEdgeDriver=103.0.1264.62
I would be very grateful if I could get your help.

Answer 1

This cookie is set to ensure that browsers that support SameSite cookies can check to see if a request originates from GitHub.
You will find only this cookie have a different value of Strict in the sameSite attribute, others being Lax. So when you skip this cookie, everything works fine. You can set this cookie separately by adding this code:
driver.add_cookie({'name':'__Host-user_session_same_site','value': 'itsValue','sameSite':'Strict'})