static void Main()
var driver = new FirefoxDriver(options); // will search PATH driver.Navigate().GoToUrl("https://example.com"); Console.WriteLine(driver.Title); driver.Quit();
// Ensure geckodriver.exe is in the same folder as your .exe or in PATH var options = new FirefoxOptions(); options.AddArgument("--headless"); // optional: headless mode
foreach (var process in Process.GetProcessesByName("geckodriver")) process.Kill(); Force a specific, free port to avoid conflicts. static void Main() var driver = new FirefoxDriver(options);
taskkill /F /IM geckodriver.exe
service = FirefoxDriverService.CreateDefaultService(); service.LogPath = "geckodriver.log"; service.LogLevel = FirefoxDriverLogLevel.Trace; var driver = new FirefoxDriver(service); Check geckodriver.log – it will show port binding failures, binary issues, or profile problems. using OpenQA.Selenium.Firefox; class Program
Introduction If you are automating Firefox using Selenium WebDriver in C# (or any .NET language), you have likely encountered the dreaded WebDriverException : "Cannot start the driver service on http://localhost..." This error stops your automation dead in its tracks. It means Selenium cannot communicate with the geckodriver (the bridge between your code and Firefox). It means Selenium cannot communicate with the geckodriver
Below, I break down exactly why this happens and the 7 most effective fixes. OpenQA.Selenium.WebDriverException: Cannot start the driver service on http://localhost:xxxx/ ---> System.Net.Sockets.SocketException: Only one usage of each socket address (protocol/network address/port) is normally permitted. Root Cause Analysis The error indicates a port conflict or driver process failure . The geckodriver tries to bind to a port on localhost , but something is blocking it.
FirefoxDriverService service = FirefoxDriverService.CreateDefaultService(@"D:\drivers"); service.FirefoxBinaryPath = @"C:\Program Files\Mozilla Firefox\firefox.exe"; var driver = new FirefoxDriver(service); Sometimes a corrupted Firefox profile causes the driver to hang on startup.
GitHub mozilla/geckodriver 4. Add Driver Path to System PATH (or specify explicitly) Option A – Add to PATH: Place geckodriver.exe in a folder already on PATH, or add its folder to system environment variables. Root Cause Analysis The error indicates a port
pkill -f geckodriver
// No need to set driver path anymore var driver = new FirefoxDriver(); // Selenium Manager handles geckodriver Update your NuGet packages to Selenium.WebDriver 4.6 or higher. Let me know in the comments which fix worked for you, or share your geckodriver.log for more help!
var service = FirefoxDriverService.CreateDefaultService(@"C:\path\to\geckodriver"); service.Port = 12345; // Use any free port above 1024 var driver = new FirefoxDriver(service); | Firefox Version | GeckoDriver Version | |----------------|---------------------| | 115+ (ESR) | 0.33+ | | 120+ | 0.34+ | | 130+ | 0.35+ |