Selenium: The environment you requested was unavailable

I was trying to run the test using gemini on firefox (v50.0.2), although the firefox browser opened successfully, it didn't open the url in the address bar. Then in the terminal I saw this error message:

Cannot launch browser firefox: [init({"browserName":"firefox"})] The environment you requested was unavailable.

Command:

sudo gemini update test.js

Code:

module.exports = {
    rootUrl: 'http://example.com',
    gridUrl: 'http://127.0.0.1:4444/wd/hub',

    browsers: {
        chrome: {
           desiredCapabilities: {
              browserName: 'chrome'
           }
        },
        'firefox-latest': {
            desiredCapabilities: {
                browserName: "firefox"
            }
        }
    }
};

The test runs successfully on chrome browser. I'm running MacOSX Sierra.

There was broken changes with FF driver. And wd tool doesn't support it yet. It works with firefox v46 and below.

https://github.com/gemini-testing/gemini/issues/688#issuecomment-267984936