Cannot Start The Driver Service On Http Localhost Selenium Firefox C 95%

Firefox updates automatically in the background. If Firefox updates to a new version (e.g., v120) but your NuGet package Selenium.WebDriver.GeckoDriver is stuck on an older release (e.g., v115), the driver will crash instantly upon startup.

This error message (or variations of it) is one of the most common hurdles when setting up Selenium with Firefox in C#. It essentially means your C# code tried to launch the Firefox driver, but the driver process ( geckodriver.exe ) failed to start or crashed immediately. Firefox updates automatically in the background

Technical Incident Report: Selenium WebDriver Initialization Error It essentially means your C# code tried to

// Replace with the actual folder path containing geckodriver.exe string driverPath = @"C:\Your\Path\To\Drivers"; var service = FirefoxDriverService.CreateDefaultService(driverPath); IWebDriver driver = new FirefoxDriver(service); Use code with caution. Clear them out using (Run as Admin): taskkill

options = webdriver.FirefoxOptions() options.binary_location = r'C:\Program Files\Mozilla Firefox\firefox.exe'

One of the most common causes is multiple background driver instances hogging the port or local resources. Clear them out using (Run as Admin): taskkill /f /im geckodriver.exe taskkill /f /im firefox.exe 2. Verify Your FirefoxDriver Constructor