Selenium Firefox C [2021] - Cannot Start The Driver Service On Http Localhost

FirefoxDriverService service = FirefoxDriverService.CreateDefaultService(); IWebDriver driver = new FirefoxDriver(service, new FirefoxOptions(), TimeSpan.FromSeconds(120));

Always call driver.Quit() and driver.Dispose() in your test teardown methods to prevent orphaned processes.

When the error appears, follow this systematic checklist: FirefoxDriverService service = FirefoxDriverService

That will help narrow down the exact issue.

If your C# client cannot establish this initial local HTTP handshake with the freshly started geckodriver.exe process within a default 2-second timeout window, the runtime throws the exception. 5 Common Causes and Their Solutions 5 Common Causes and Their Solutions How to

How to Fix Selenium Error: "Cannot start the driver service on http://localhost" with Firefox in C#

// 3. Pass the service to the driver constructor IWebDriver driver = new FirefoxDriver(service); Ensure the architecture (x64 vs x86) matches your

You can explicitly force the GeckoDriverService to use the IPv4 loopback address ( 127.0.0.1 ) instead of the word localhost .

using (var driver = new FirefoxDriver())

Security software is blocking the executable from starting a local web server.

Ensure the architecture (x64 vs x86) matches your operating system. 4. Add a "NO_PROXY" Environment Variable