selenium connection refused to chromedriver: how to fix

TL;DR

The chromedriver process is not listening where Selenium expects. Start it explicitly or let Selenium Manager handle it, check the port is free, and kill stale driver processes.

Error

urllib3.exceptions.NewConnectionError: Failed to establish a new connection: [Errno 111] Connection refused

Steps

1. Check for stale chromedriver processes: ps aux | grep chromedriver. Kill them. Expected: no zombies holding the port.
2. Let Selenium Manager start the driver (Selenium 4.6+ default). Expected: no manual driver management.
3. If starting manually, use a free port: chromedriver --port=9516 and point Selenium at it. Expected: no port conflict.
4. Check the driver log for crash lines at startup. Expected: the real startup error, if any.
5. Re-run. Expected: Selenium connects.

When to use

• Connection refused naming chromedriver's port.
• After killing hung runs.

When not to use

• Browser fails after the driver connects (browser issue).
• Grid setups (hub/node networking).

Tool compatibility

• Selenium 4.x; chromedriver matching Chrome.

Variant phrasings

Failed to establish a new connection to chromedriver

The urllib3 form; same fix.

chromedriver connection refused in CI

Stale processes from prior jobs; clean the workspace.

Why it happens

The driver is a separate HTTP server. If it crashed, never started, or a zombie holds its port, Selenium cannot connect.

Edge cases

• CI runners that reuse workspaces accumulate zombies; clean processes in a pre-step.
• Port 9515 conflicts with parallel jobs; assign ports per job.
• Driver logs go to stderr by default; capture them in CI.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_Hn8cmYJlyQ4BK0OeGcGGuw