org.openqa.selenium.SessionNotCreatedException: Unable to find a matching set of capabilities while trying to launch Firefox with Selenium v3.8.1

Question

I am not able to launch Firefox browser using geckodriver in Selenium 3.8.1

This is my code

public class LoginTest {
    @SuppressWarnings("deprecation")
    @Test
    public static void logintest() {
        System.setProperty("webdriver.gecko.driver",
            "C:\\Users\\abc\\Downloads\\geckodriver.exe");
        DesiredCapabilities dc = DesiredCapabilities.firefox();
        dc.setCapability("marionnete", true);
        constants.driver = new FirefoxDriver(dc);
        constants.driver.get("https://www.amazon.in");
        constants.driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
        constants.driver.manage().window().maximize();
    }

I am not able to understand why it is not working and always giving an exception

org.openqa.selenium.SessionNotCreatedException`: Unable to find a matching set of capabilities
Build info: version: '3.8.1', revision: '6e95a6684b', time: '2017-12- 01T18:33:54.468Z'<br>
System info: host: 'ABC-VAIO', ip: '192.168.1.209', os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.8.0_161'<br>
Driver info: driver.version: FirefoxDriver

Answer 1

This error message...

org.openqa.selenium.SessionNotCreatedException: Unable to find a matching set of capabilities

...implies that the FirefoxDriver didn't find a matching set of capability while initiating a new WebBrowser session.

You are using Selenium Client v3.8.1 but the Release Notes of Selenium Client v3.7.0 clearly states that :

* Migrated from using `DesiredCapabilities` to either
  `MutableCapabilities` or (preferably) `ImmutableCapabilities`.

So, you have to use the merge() method from MutableCapabilities Class to add the capabilities within an instance of FirefoxOptions and pass the FirefoxOptions object while initializing the Firefox Browser as follows :

System.setProperty("webdriver.gecko.driver", "C:\\Users\\abc\\Downloads\\geckodriver.exe");
DesiredCapabilities dc = DesiredCapabilities.firefox();
dc.setCapability("marionnete", true);
FirefoxOptions opt = new FirefoxOptions();
opt.merge(dc);
constants.driver = new FirefoxDriver(opt);
constants.driver.get("https://www.amazon.in");

Answer 2

You should add capabilities for firefox Please modify your code as follows :

System.setProperty("webdriver.gecko.driver", "C:\\Selenium\\geckodriver.exe");
DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities = DesiredCapabilities.firefox();
capabilities.setBrowserName("firefox");
capabilities.setVersion("your firefox version");
capabilities.setPlatform(Platform.WINDOWS);
capabilities.setCapability("marionette", false);
WebDriver driver = new FirefoxDriver(capabilities);
driver.get("https://www.amazon.in");