What happened?

An error occurs when trying to set a proxy auto-configuration URL using setProxyAutoconfigUrl() in a FirefoxOptions object. The geckodriver is not able to launch, and the following error is thrown:

org.openqa.selenium.remote.NoSuchDriverException: Unable to obtain: geckodriver, error Command failed with code: 2, executed: [--browser, firefox, --browser-version, 129.0, --proxy, --language-binding, java, --output, json]
error: a value is required for '--proxy ' but none was supplied

For more information, try '--help'.

How can we reproduce the issue?

FirefoxOptions firefoxOptions = new FirefoxOptions();
firefoxOptions.setBrowserVersion("129.0");

Proxy proxy = new Proxy();
proxy.setProxyAutoconfigUrl("http://web-proxy/proxy.pac");
			
firefoxOptions.setProxy(proxy);

new FirefoxDriver(firefoxOptions);

Relevant log output

org.openqa.selenium.remote.NoSuchDriverException: Unable to obtain: geckodriver, error Command failed with code: 2, executed: [--browser, firefox, --browser-version, 129.0, --proxy, --language-binding, java, --output, json]
error: a value is required for '--proxy <PROXY>' but none was supplied

For more information, try '--help'.

Operating System

Macos

Selenium version

selenium-server-4.23.0.jar

What are the browser(s) and version(s) where you see this issue?

Firefox version 130.0

What are the browser driver(s) and version(s) where you see this issue?

geckodriver 0.35.0

Are you using Selenium Grid?

No response