Right-click your project -> Manage NuGet Packages -> Update Selenium.WebDriver and Selenium.WebDriver.GeckoDriver .
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#
Ensure Firefox is updated to the latest stable release. 3. Configure Firewall Exceptions Right-click your project -> Manage NuGet Packages ->
The error is a common headache for C# developers using Selenium with Firefox. It typically means the GeckoDriver executable is unable to establish a local network connection to start its internal server. 🛠️ Root Causes Port Conflicts: Another process is using the default port. Loopback Issues: localhost isn't resolving to 127.0.0.1 .
using (IWebDriver driver = new FirefoxDriver()) { try { driver.Navigate().GoToUrl("https://google.com"); } catch (Exception ex) { Console.WriteLine($"Error: {ex.Message}"); } } // Automatically calls Quit() and closes the service Use code with caution. 🔍 Troubleshooting Summary Ensure port 4444 (or your custom port) is free. Path Verify geckodriver.exe is in your bin folder. VPN Turn off VPNs, as they can sometimes reroute local traffic. Permissions Run Visual Studio as Administrator. End all tasks named geckodriver
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.
Security software is blocking the driver's execution. Right-click your project -> Manage NuGet Packages ->
Ensure you aren't running an old version of GeckoDriver with a brand-new version of Firefox.