Cannot Start The Driver Service On Http Localhost Selenium Firefox C Jun 2026

Download the matching from the official repository . Troubleshooting Quick Tips

If you haven't already, you need to install the specific Selenium wrapper for Firefox. Download the matching from the official repository

If you see an error like “cannot start the driver service on http://localhost:xxxxx” when using Selenium with Firefox in C#, this note explains common causes and fixes. Download the matching from the official repository

// Now initialize the driver IWebDriver driver = new FirefoxDriver(); Download the matching from the official repository

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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#