Cannot Start The Driver Service On Http Localhost Selenium Firefox C Extra Quality -

Since GeckoDriver starts a local web server to communicate with your code, firewalls might flag it as "unauthorized network activity." Temporarily disable your firewall to test.

Right-click your project -> Manage NuGet Packages -> Update Selenium.WebDriver and Selenium.WebDriver.GeckoDriver .

Ensure you aren't running an old version of GeckoDriver with a brand-new version of Firefox. Since GeckoDriver starts a local web server to

Sometimes Selenium struggles to resolve the string "localhost." Forcing it to use the IPv4 loopback address often bypasses DNS or hostfile issues.

Security software is blocking the driver's execution. driverService.Host = "127.0.0.1"

var driverService = FirefoxDriverService.CreateDefaultService(); driverService.Host = "127.0.0.1"; // Force IPv4 IWebDriver driver = new FirefoxDriver(driverService); Use code with caution. 2. Update Drivers and Browser

To prevent this error in the future, always wrap your driver initialization in a try-catch block and ensure you call driver.Quit() in a finally block or a using statement. Use code with caution.

If a previous debug session crashed, a "ghost" instance of GeckoDriver might still be holding onto the port. Open . End all tasks named geckodriver.exe . End all tasks named firefox.exe . 📋 Best Practices for C#

If it works, add an exception for geckodriver.exe in your Windows Defender or Antivirus settings. 4. Clean Up Hanging Processes

📍 Most "localhost" service errors are solved by explicitly setting the Host to 127.0.0.1 in the DriverService object. AI responses may include mistakes. Learn more