“Unknown command received” errors using MicrosoftW

Question

I am using Selenium (v2.47) and the Microsoft Web Driver (v10.0.10240.0). I am working with some existing C# code that already runs fine on Firefox, IE and Chrome and I want to use it to test the new Edge browser on Windows 10. My code is able to successfully open the browser and navigate to my login page. However I get an "Unknown command received" exception when I do a few basic things such as:

1) maximize the browser

2) call .FindElement(by) on an existing IWebElement.

For example:

driver.Manage().Window.Maximize(); //throws exception

...

IWebElement parent = driver.FindElement(By.TagName("body")); //works

...

parent.FindElement(by); //throws exception

Has anyone seen either of these work with Selenium and C# for the Edge browser? Maybe I am doing something wrong here. Or does "Unknown command received" just mean it is unimplemented functionality that will come in the future?

Answer 1

There was a fair amount of missing functionality in the initial (10.0.10240) Edge driver release, including missing support for IWebElement.FindElement(). Subsequent releases, which also required an update to Edge itself via Windows 10 updates, and until very recently only available via so-called Insider builds. A full accounting of what was implemented and when is provided by Microsoft at their WebDriver implementation status page.