Selenium File Upload Fails With Error: "post Did Not Match A Known Command"

When I attempt to upload a file with selenium 3.3.0 I get the following error message: selenium.common.exceptions.WebDriverException: Message: POST (...) did not match a known comm

Solution 1:

Looks like it's a bug in Selenium. As a workaround, add driver._is_remote = False after the driver = webdriver.Firefox() line.

See https://stackoverflow.com/a/42770761/373915 for details.