This is a warning message. The native code (C++) component of the IE driver includes an HTTP server, since the driver uses the JSON Wire Protocol for its communications. That HTTP server takes a small amount of time to start and be ready to receive HTTP requests. However, the RemoteWebDriver’s HTTP client (remember that InternetExplorerDriver is a subclass of RemoteWebDriver) cannot know exactly when that server is available, so this causes a race condition. The HTTP client must poll the server until it receives a valid response. When you’re seeing this warning, it’s only telling you that the internal HTTP server hasn’t completed its initialization, and the HTTP client has lost the race. It should be harmless, and you should be able to safely ignore it.