Cannot Start The Driver Service On Http Localhost Selenium Firefox C __top__

If your Firefox updated itself but your GeckoDriver is old, they might literally speak different "languages".

Can you open Firefox normally? If not, reinstall.

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

If you are using a separate driver deployment package like Selenium.WebDriver.GeckoDriver , update that as well, or remove it entirely to let Selenium Manager handle the binaries automatically. 4. Configure Antivirus and Firewall Exceptions If your Firefox updated itself but your GeckoDriver

driver = webdriver.Firefox(service=service)

If a previous debug session crashed, an instance of geckodriver.exe might still be "hanging" on the port. Open .

Open terminal/cmd: geckodriver --version If "command not found", fix PATH. If your C# client cannot establish this initial

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

This usually appears alongside messages about geckodriver not being found, failing to start, or timing out. Let’s break down why this happens and exactly how to fix it.

Set the Variable name to NO_PROXY and the Variable value to localhost,127.0.0.1 . failing to start

try

Happy testing — and may your driver services always start on the first try.

Increase the command timeout when initializing the FirefoxDriver:

Compatibility issues between the browser and driver are a frequent cause of startup failures. Stack Overflow Version Match: Ensure your geckodriver version supports your current Firefox version. Architecture: Check if you are running a binary on a

System.setProperty("webdriver.gecko.driver", "/usr/local/bin/geckodriver");