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

Restart your IDE (Visual Studio / Rider) for the changes to take effect. 2. Terminate Hanging Background Processes

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

Ensure your firewall is not blocking 127.0.0.1 or the specific port mentioned in the error message. 4. Increase the Driver Service Timeout

The system cannot find the geckodriver.exe file. 1. Match Your Versions Restart your IDE (Visual Studio / Rider) for

If the error persists after trying the fixes above, verify the following configurations: Verification Step

If none of the above works, reset the entire ecosystem:

The executable_path parameter is deprecated in newer Selenium versions (4+). Use service instead (see advanced section). Increase the Driver Service Timeout The system cannot

In this long-form guide, we will dissect every possible cause of the error, explain the underlying architecture of Selenium and Firefox, and provide step-by-step solutions—from quick fixes to deep debugging techniques.

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

Cannot start the driver service on http://localhost #372 - GitHub If it fails

If you use webdriver_manager.firefox.GeckoDriverManager , update it:

Selenium attempts to locate geckodriver in your system’s PATH environment variable or at a path you specified. If it fails, it cannot start the service.