Cannot Start The Driver Service On Http Localhost Selenium Firefox C !!exclusive!! ❲macOS❳

Note: Even if you specify the path, ensure geckodriver.exe matches the version of your installed Firefox browser. If you updated Firefox today, your driver might be obsolete.

If you are running your C# Selenium tests in a CI/CD pipeline (such as Azure DevOps, GitHub Actions, or Docker containers), the lack of a display monitor or specific environment arguments will cause the driver service to fail immediately.

driver.Navigate().GoToUrl("https://google.com");

If you are manually defining a FirefoxDriverService , ensure you aren't passing the path to the itself where the code expects the geckodriver executable. Note: Even if you specify the path, ensure geckodriver

Open terminal/cmd: geckodriver --version If "command not found", fix PATH.

The error occurs only in CI/CD (Jenkins, GitLab CI) but works on your local desktop.

pip install --upgrade webdriver-manager

Force the FirefoxDriverService to utilize a specific, available port to circumvent default port conflicts.

— a brute-force but effective way to clear all stale processes.

from selenium import webdriver from selenium.webdriver.firefox.service import Service driver

This error frequently appears in CI/CD environments where test agents lack proper configuration. Here are targeted solutions for pipeline environments:

| Firefox Version | Minimum GeckoDriver Version | |----------------|-----------------------------| | Firefox 115+ | v0.33.0+ | | Firefox 100-114| v0.31.0+ | | Firefox 90-99 | v0.29.0+ |