"InvalidArgumentException: Message: binary is not a Firefox executable error using GeckoDriver Firefox Selenium and Python"

Solution for InvalidArgumentException in Selenium

The error message "selenium.common.exceptions.InvalidArgumentException: Message: Binary is not a Firefox executable" in Selenium typically occurs when the WebDriver is unable to locate or execute the Firefox browser binary specified in your Selenium script or configuration.

Possible Causes:

  • Incorrect path to the Firefox browser binary specified in your Selenium script or configuration.
  • The specified file is not an executable Firefox binary.
  • Version mismatch between Selenium WebDriver and Firefox browser.


  1. Verify Firefox Binary Path: Double-check the path to the Firefox browser binary specified in your Selenium script or configuration. Ensure that it points to the correct location of the Firefox executable on your system.
  2. Download and Install Firefox: If you haven't already done so, download and install the Firefox browser on your system. Make sure to install the correct version that is compatible with your Selenium WebDriver.
  3. Update Selenium WebDriver: Ensure that you are using the latest version of Selenium WebDriver that is compatible with the version of Firefox installed on your system. You can update Selenium WebDriver using package managers like pip (for Python) or Maven (for Java).
  4. Check File Permissions: Ensure that the Firefox executable file has the necessary permissions to be executed. On Unix-like systems, you can use the chmod command to set executable permissions (e.g., chmod +x firefox).
  5. Use GeckoDriver: Selenium WebDriver requires GeckoDriver to interact with Firefox. Make sure you have downloaded and configured GeckoDriver properly. Specify the path to GeckoDriver in your Selenium script or set it in the system PATH variable.
  6. Test with Absolute Path: Instead of relying on relative paths, specify the absolute path to the Firefox binary in your Selenium script. This ensures that Selenium can locate the binary correctly regardless of the working directory.

After applying the above steps and ensuring that the correct Firefox binary is specified and accessible to Selenium WebDriver, rerun your Selenium script to see if the error persists.

I resolved it by updating to the latest version of Selenium, which is version 4.16.0.
Ensure that your Selenium, Firefox, and geckodriver versions are compatible with each other. You can find a list of compatible versions here: Geckodriver Compatibility. In my case, I downgraded Selenium from version 4 to 3.11, upgraded Firefox to version 120, and used geckodriver version 0.33.
Change the binary to whatever firefox.exe you get and your executable path to your geckodriver. options = Options() binary = r'C:\Program Files\Mozilla Firefox\firefox.exe' options.set_preference("browser.download.folderList",2) options.set_preference("browser.download.manager.showWhenStarting", False) options.set_preference("browser.download.dir","/Data") options.set_preference("browser.helperApps.neverAsk.saveToDisk", "application/octet-stream,application/vnd.ms-excel") options.binary = binary driver = webdriver.Firefox(r'C:/Users/ashok/AppData/Local/Programs/Python/Python38-32/geckodriver-v0.27.0-win64/geckodriver.exe',options=options)