Selenium 4 - Unable to set Chrome download.default_directory

[chadnorris]

💥 Regression Report

This python code is working with Selenium 3.141 but is not in 4.0.0.b1. I see a warning - Expected type 'Union[str, int]', got 'dict[str,str]' instead. The documentation I see on this shows prefs is a dictionary (https://chromedriver.chromium.org/capabilities).

options = webdriver.ChromeOptions()
prefs = {'download.default_directory': 'C:\Temp'}
options.add_experimental_option('prefs', prefs)

Last working Selenium version

Worked up to version: 3.141

Stopped working in version: 4.0.0.b1

To Reproduce

from selenium import webdriver

options = webdriver.ChromeOptions()
prefs = {'download.default_directory': 'C:\Temp'}
options.add_experimental_option('prefs', prefs)
driver = webdriver.Chrome(options=options)
driver.maximize_window()
driver.get("https://www.seleniumhq.org/download/")
laa = driver.find_element_by_link_text("32 bit Windows IE")
laa.click()

Detailed steps to reproduce the behavior:

Expected behavior

Default Download Directory set to specified directory and file is downloaded there. C:\Temp in this example.

Test script reproducing this issue (when applicable)

options = webdriver.ChromeOptions()
prefs = {'download.default_directory': 'C:\Temp'}
options.add_experimental_option('prefs', prefs)

Environment

OS: Windows 10
Browser: Chrome
Browser version: 88.0.4324.190
Browser Driver version: 88.0.4324.96
Language Bindings version: Python 3.9.2
Selenium Grid version (if applicable): N/A