python 3.x - Is Chrome installation needed or only chromedriver when using Selenium?

Question

I've tried to search, but haven't found a definitive answer. On Windows Server 2016 WITHOUT Chrome Browser actually installed. I downloaded the correct "chromedriver.exe" and placed it in "D:Appschromedriver.exe". I have added to my environment PATH the full path as "D:Appschromedriver.exe".

When I attempt to start my Windows Service that utilizes the latest Selenium, I get the following error:

Exception occurred: Failed initializing web driver: Message: unknown error: cannot find Chrome binary
  (Driver info: chromedriver=2.40.565498 (ea082db3280dd6843ebfb08a625e3eb905c4f5ab),platform=Windows NT 10.0.14393 x86_64)

Question: Do I have to actually install the full-blown browser in addition to the chromedriver, or is this simply just not finding the chromedriver.exe in my Python code (included below for full disclosure):

def __init__(self, username, password, environment='cert'):
    self.username = username
    self.password = password
    self.environment = environment

    # Instantiate a chrome options object so you can set the size and headless preference
    self.chrome_options = Options()

    # Toggle Headless or not
    if HEADLESS_TOGGLE == 1:
        self.chrome_options.add_argument("--headless")

    self.chrome_options.add_argument("--disable-gpu")  # Disables "Lost UI Shared Context GPU Error on Windows"
    self.chrome_options.add_argument('--disable-extensions')  # Disables Extensions
    self.chrome_options.add_argument("--disable-software-rasterizer")  # Disables "Lost UI Shared Context GPU Error on Windows"
    self.chrome_options.add_argument("--window-size=1024x768")
    self.chrome_options.add_argument("--log-level=3")  # Errors Only
    self.chrome_options.add_argument("--incognito")  # Keeps history and logs clear
    self.chrome_options.add_argument("--no-sandbox")
    self.chrome_options.add_argument("--mute_audio")  # No loud surprises!
    self.chrome_options.add_argument("--no-gpu")  # Disables gpu-based errors (headless)

    self.driver = webdriver.Chrome(chrome_options=self.chrome_options)

Answer 1

This error message...

Exception occurred: Failed initializing web driver: Message: unknown error: cannot find Chrome binary
  (Driver info: chromedriver=2.40.565498 (ea082db3280dd6843ebfb08a625e3eb905c4f5ab),platform=Windows NT 10.0.14393 x86_64)

...implies that the ChromeDriver was unable to find the Chrome binary while trying to initiate a new new Browsing Context i.e. Chrome Browser session.

---

As per the documentation with in the wiki page of ChromeDriver:

• ChromeDriver is a standalone server which earlier implemented the WebDriver's wire protocol but slowly and gradually shifting it's implementation as per WebDriver standard.

• The ChromeDriver consists of three separate pieces.

  • There is the browser itself i.e. chrome
  • The language bindings provided by the Selenium project i.e. the driver
  • An executable downloaded from the Chromium project which acts as a bridge between chrome and the driver which is called chromedriver and we refer to it as the server.
• In generic scenarios the server expects you to have Chrome installed in the default location for each system:
  • Linux: /usr/bin/google-chrome ¹
  • Mac: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
  • Windows XP: %HOMEPATH%Local SettingsApplication DataGoogleChromeApplicationchrome.exe
  • Windows Vista and newer: C:Users\%USERNAME%AppDataLocalGoogleChromeApplicationchrome.exe

Note: ¹: For Linux systems, the ChromeDriver expects /usr/bin/google-chrome to be a symlink to the actual Chrome binary.

You can find a detailed discussion on overriding the default Chrome binary location in WebDriverException: unknown error: cannot find Chrome binary error with Selenium in Python for older versions of Google Chrome

---

Solution

So ideally to execute your tests using ChromeDriver / Chrome combo you need to:

• Install the full-blown google-chrome browser.
• Download the compatible version of chromedriver.exe
• Quick installation of ChromeDriver:
  • Mac users with Homebrew: brew tap homebrew/cask && brew cask install chromedriver
  • Debian based Linux distros: sudo apt-get install chromium-chromedriver
  • Windows users with Chocolatey installed: choco install chromedriver
• You can find a couple of relevant discussions in:
  • How to work with a specific version of ChromeDriver while Chrome Browser gets updated automatically through Python selenium
  • Selenium for ChromeDriver and Chrome Browser and the log message “Only local connections are allowed”
  • WebDriverException: Message: Service /usr/lib/chromium-browser/chromedriver unexpectedly exited on Raspberry-Pi with ChromeDriver and Selenium

---

Reference

You can find a detailed discussion in:

• WebDriverException: unknown error: cannot find Chrome binary error with Selenium in Python for older versions of Google Chrome