Selenium "SessionNotCreatedException" - Driver/Browser Mismatch

By Kaveh Alemi·Latchkey

Selenium could not start a browser session. The most common cause is a ChromeDriver/Chrome version mismatch - the driver only supports a specific major Chrome version, and the installed browser is different.

What this error means

Session creation fails with "SessionNotCreatedException: ... This version of ChromeDriver only supports Chrome version N. Current browser version is M." It happens after Chrome auto-updates on the runner but the pinned driver does not.

Selenium output

selenium.common.exceptions.SessionNotCreatedException: Message: session
not created: This version of ChromeDriver only supports Chrome version 124
Current browser version is 131.0.6778.85

Common causes

Driver and browser major versions differ

A pinned ChromeDriver (124) cannot drive a newer Chrome (131). The driver speaks only to its matching major version.

Hardcoded driver path overriding auto-resolution

An explicit old driver binary on PATH or via Service(executable_path=...) shadows Selenium Manager’s automatic matching.

How to fix it

Let Selenium Manager resolve the driver

Selenium 4.6+ ships Selenium Manager, which downloads a matching driver automatically - drop the hardcoded path.

test_app.py

# Python: just let Selenium Manager pick the driver
from selenium import webdriver
driver = webdriver.Chrome()   # no Service(executable_path=...)

Or pin browser and driver together

Install a fixed Chrome version in CI instead of tracking latest.
Install the matching ChromeDriver major version alongside it.
Upgrade Selenium to 4.6+ so Manager handles matching for you.

How to prevent it

Use Selenium 4.6+ and let Selenium Manager match the driver.
If you pin Chrome, pin the matching driver in the same step.
Avoid auto-updating the browser without updating the driver.

Frequently asked questions

What causes ""SessionNotCreatedException""?