nightwatch is configured as follows

// nigthwatch.json
{
  "src_folders" : ["examples"],
  "output_folder" : "output",
  "webdriver" : {
    "start_process": true,
    "log_path": "output",
    "port": 4444
  },

  "test_settings" : {
    "default" : {
      "desiredCapabilities": {
        "browserName": "firefox",
        "acceptInsecureCerts": true
      }
    }
  }
}

the same configuration starts chrome smoothly, but starts firefox without any reaction or error, so I am helpless.

official website also says that nightwatch 1.0 is no longer needed for Selenium Server support. What is the problem?