I am running tests on selenium grid using nunit C# with:

  • selenium-standalone-server: v3.3.1
  • selenium webdriver: v3.3
  • geckodriver: 0.15
  • firefox: v52

Firefox is not installed on the default location and so I get following exception on running tests:

Expected browser binary location, but unable to find binary in default location, no 'moz:firefoxOptions.binary' capability provided, and no binary flag set on the command line (WARNING: The server did not provide any stacktrace information)

I want to specify Firefox executable path on the capabilities section of node.config file of selenium grid. How do I do that with new geckodriver?

firefox_binary is now obsolete and it uses "moz:firefoxOptions", but I don't know how to specify it in selenium node's config file.

This is what I am doing in the config file, but it's not working:

      "platform": "WINDOWS",
      "browserName": "firefox",
      "moz:firefoxOptions": {
        "binary": "D:\\Browsers\\Mozilla Firefox\\firefox.exe"
      "maxInstances": 1,
      "seleniumProtocol": "WebDriver"

1 Answer 1


Unfortunatelly I found only workaround solution (e.g. if you need several different Firefox versions on a single station):


  "capabilities": [
      "browserName": "firefox",
      "version": "51",
      "platform": "WINDOWS",
      "maxInstances": 1,
      "cleanSession": true


set "PATH=%PATH%;C:\Program Files\Mozilla Firefox\51" 
java -jar -Dwebdriver.gecko.driver=C:\Apps\Selenium\Grid\drivers\geckodriver.exe selenium-server-standalone-3.3.1.jar -role node -nodeConfig nodeConfig_1.json

As you can guess, for other Firefox binaries you can use simmilar .cmd scripts.

  • Thanks. I am using the same solution. I could not find any documentation online on how to utilize .config file for this.
    – H.D.
    Jun 26, 2018 at 16:53

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