I am trying to move into the upgraded firefox web browser automation using selenium. It seems that selenium needs marionette driver to continue working. I followed the instr
I too got the "Entity Not Found" error using FirefoxDriver(new FirefoxOptions()). It appears to be looking for firefox.exe in C:\Program Files (x86)\Nightly and not finding it. I found this working :
FirefoxDriverService service = FirefoxDriverService.CreateDefaultService();
service.FirefoxBinaryPath = @"C:\Program Files (x86)\Mozilla Firefox\firefox.exe";
IWebDriver driver = new FirefoxDriver(service);