Starting from version 1.3.0, we are working with standard Chrome and Firefox browsers instead of their portable versions.
If during a web action execution you get the following exception:
org.openqa.selenium.WebDriverException: unknown error: call function result missing 'value’
your browser has updated, and you need to update the webdriver.
To do it, you need to follow the simple steps from the troubleshooting guide: https://kb.workfusion.com/display/RPAe/Troubleshooting#expand-ErrorexecutingWebElementAction