Mozilla Firefox: Unable to launch the browser or run automated tests


Improper configuration of the Mozilla Firefox browser results in one of the following negative cases:

  • Upon the completion of a test run, the Firefox browser is not launched successfully, and the following warning message appears in the test result of the navigate built-in action. WebDriver for Firefox is not launched yet. Please start WebDriver, and try again.
  • You have already launched Firefox manually, and then run the automation playback. However, you do not use the navigate built-in action in your test. The playback is unable to properly match web controls. Hence, for example, a check control exists built-in action would produce a Failed result despite the existence of the target control.


This issue occurs because GeckoDriver is not started on your machine. Stop the currently running test and refer to configuration steps to resolve this issue.