# What changed in selenium

> 12 changes in selenium 4 from its official release notes, upgrade guides and advisories: 8 breaking, 4 deprecations. Each one cited. Sources checked 2026-10-29. HTML: https://unstale.sh/pypi/selenium/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## selenium 4

### Breaking changes

- Use browserVersion instead of version in W3C-compliant capabilities. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- Java timeout and wait APIs now expect Duration instead of a time and TimeUnit pair or a numeric timeout. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- The Java binding utility methods for finding elements, including findElement* and findElements*, are removed; use findElement or findElements with By instead. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- Merging capabilities no longer mutates the calling object; assign the result of the merge operation. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- Use platformName instead of platform in W3C-compliant capabilities. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- Selenium 4 requires Python 3.7 or higher. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- Capabilities not in the W3C standard list need a vendor prefix, such as a cloud vendor's cloud:options block. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- Selenium 4 removes support for the legacy protocol and uses the W3C WebDriver standard by default. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)

### Deprecations

- The C# API is deprecated; use AddAdditionalOption instead. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- BrowserType is deprecated in favour of the Browser interface. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- Python driver construction deprecates executable_path; pass a Service object or ensure the driver is on the System PATH. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)
- The Firefox legacy driver option is deprecated; the notes recommend relying only on GeckoDriver. (4.0.0) — [upgrade guide](https://www.selenium.dev/documentation/webdriver/troubleshooting/upgrade_to_selenium_4)