Solved
FireFox Error "Cannot find any existing or open blank page"?
We have a test with a browser loop containing Chrome, IE, FireFox. The test runs fine in Chrome & IE, but FF gets "Cannot find any existing or open blank page" when navigating to our main site at the...
Go to Help -> Check for Updates and make sure you have the latest Firefox support update. I think something has been released recently so it might be worth the check.
