Can you try using it on different browser and see if it gives the same error.
I determined that, in my environment, the Chrome Native Messaging capability within Chrome itself was broken, determined by finding a few other Google Extensions from the Play store that required this capability, none of which worked.
So - not a UIPath problem, but a Chrome one, despite running the latest version of Chrome.
The fix was to uninstall and re-install Chrome - remembering to install from https://google.com/chrome (to avoid the multitude of 3rd party Chrome builds that come up top in the search page rankings, which come bundled with hidden Spyware)
i am doing this on IE
step1 :Use Attach window activity and inside the container click on the"Indicate window on screen" and here select your IE/Chrome whole window, which has the output variable as windows type ,give some variable name (X) in the property section.
step2: inside the “do” container use the “Maximize activity” and pass the window variable(X) as the input.
step 3: As browser is dynamic you need to modify the selector by clicking on “attach the live element” from selector editor and click on the browser window.
Since you are doing this on IE, did you try using the attach browser activity instead of the attach window activity and place the maximize window activity inside that?
That should work for you… In the workflows I have used this, I used it in a attach browser activity and it worked without a problem