Getting error "org.openqa.selenium.WebDriverException: java.net.ConnectException: Connection refused:"

I am using selenium webdriver for the testing application. i am using using Marionettedriver for the browser. however when I run the code it gives the error "org.openqa.selenium.WebDriverException: java.net.ConnectException: Connection refused:" I have check the system path also no issue in the same. so please suggest how to solve the error''