Cannot Start The Driver Service On Http Localhost Selenium Firefox C

// This automatically downloads and sets up the correct GeckoDriver new DriverManager().SetUpDriver(new FirefoxConfig());

This error message (or variations of it) is one of the most common hurdles when setting up Selenium with Firefox in C#. It essentially means your C# code tried to launch the Firefox driver, but the driver process ( geckodriver.exe ) failed to start or crashed immediately. // This automatically downloads and sets up the

Always ensure your NuGet package, geckodriver , and Firefox browser are all updated to compatible versions. On Windows, SmartScreen or Windows Defender may quarantine

On Windows, SmartScreen or Windows Defender may quarantine or silently block geckodriver.exe because it opens a network port (behavior associated with malware). It is a rite of passage

If this article solved your problem, consider bookmarking it for the next time you set up Selenium on a new machine. And remember: every automation engineer has faced this error at least once. It is a rite of passage.