(Chrome/Chromedriver) to isolate if issue is Firefox‑specific.
Ensure you have the latest version of geckodriver from the Mozilla Geckodriver Releases .
Based on extensive community reports and official Selenium documentation, the following are the primary reasons for this error when working with Firefox in C#. This guide breaks down exactly what this error
This guide breaks down exactly what this error means, its common root causes, and a systematic checklist to resolve it in your environments. Understanding the Architecture: Why This Happens
Another process is using the default port assigned to GeckoDriver. This executable acts as the bridge between your
IWebDriver driver = new FirefoxDriver(); driver.Url = "https://www.example.com";
. This executable acts as the bridge between your code and the Firefox browser. Selenium tries to connect to this bridge via a local network address (usually its common root causes
options = Options() options.binary_location = r'C:\Program Files\Mozilla Firefox\firefox.exe'
options = Options() options.binary_location = r'C:\Program Files\Mozilla Firefox\firefox.exe' driver = webdriver.Firefox(options=options, service=service)