sendkeys fails with error An unknown error occurred in the remote end while processing the command

My testcode will launch microsoftword and tries to type inside. Here is the code I am using

    	String application="C:\\Program Files (x86)\\Microsoft Office\\root\\Office16\\WINWORD.EXE";
    	String appWorkingDir="c:\\tmp";
    	//To suppress the splash screen and want to use blank word doc. so we use flags /q and /w flags respectively
    	String appArguments = "/q /w";
...
....
....
WebElement element =  ((WindowsDriver) webDriver).findElement("name", "Page 1 content");
		if ( element != null ) {
					element.sendKeys(keysToSend);
               }

When I debug I notice that webelement is not NULL…But sendKeys is failing on it. I get exception “An unknown error occurred in the remote end while processing the command.” I am not sure how to proceed…

WinAppDriver log

POST /wd/hub/session/7D092E3B-44FD-4C0F-957C-4F99363BEF69/element/42.1115954.2.2/value HTTP/1.1
Accept-Encoding: gzip,deflate
Connection: Keep-Alive
Content-Length: 55
Content-Type: application/json; charset=utf-8
Host: 10.173.75.51:4723
User-Agent: Apache-HttpClient/4.5.3 (Java/1.8.0_112)

{"id":"42.1115954.2.2","value":["This is sample text"]}
HTTP/1.1 500 Internal Error
Content-Length: 133
Content-Type: application/json

{"status":13,"value":{"error":"unknown error","message":"An unknown error occurred in the remote end while processing the command."}}

It will be helpful for us if you print what exactly went wrong. Please help me to proceed further.

[didhddldlq]

What makes me crazy is it sometimes work fine. But Once fails, It continuously fails. if I wait few minutes or restart computer, it works( or sometimes not!).

[ashton721]

I can also verify this issue. It only occurs for us when running tests from a tfs build agent

I can create a test that executes perfectly on the machine. If I execute the same test on the same machine via a tfs build, it fails at sendkeys with an “unknown error” it appears to be able to click find other elements without issue. SendKeys() and clear() both appear to fail