There can be three possibilities of this error as follows: WebDriver and Firefox 4+: this.getWindow() is null.

exception while clicking/inputing on any web object.It is not clear about your usecase why you require to grab the tag. As an example, the following code generates a ClassCastException: Object x = new Integer(0) However your main issue is as follows: : .Maps$TransformedEntriesMap cannot be cast to ĬlassCastException is thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. implies that WebDriverException was raised while JVM tried to cast the returned value into a WebElement. The exception I get is as follows: : Returned value cannot be converted to WebElement: However, recently I tried running it on Safari (11.1.1) on Mac OS X (10.13.5), and my script fails with a weird message even when I call a simple line such as driver.findElement(By.tagName('body')) The script works perfectly on Google Chrome, Firefox, IE, etc. I have a selenium webdriver script which performs some regression tests on my application under test.

Firefox os x 10.13