selenium: 4.0.0.b1 fails when testing file uploads

🐛 Bug Report

4.0.0.b1 fails when testing file uploads. This worked in 4.0.0a7.

Test script or set of commands reproducing this issue

Baseline successful build on 2021-01-28 with selenium-4.0.0a7: https://github.com/Pylons/deformdemo/runs/1783717797?check_suite_focus=true

Failed build on 2021-02-22 with selenium-4.0.0b1: https://github.com/Pylons/deformdemo/runs/1949937935?check_suite_focus=true

Final successful build on 2021-02-22 with selenium-4.0.0a7: https://github.com/Pylons/deformdemo/runs/1950522237?check_suite_focus=true

Stacktrace of one of four similar test failures:

______________________ FileUploadTests.test_submit_filled ______________________

self = <deformdemo.test.FileUploadTests testMethod=test_submit_filled>

    def test_submit_filled(self):
        # submit one first
        path, filename = _getFile()
>       findcss("input[type=file]").send_keys(path)

deformdemo/test.py:1466: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
.tox/py/lib/python3.8/site-packages/selenium/webdriver/remote/webelement.py:520: in send_keys
    self._execute(Command.SEND_KEYS_TO_ELEMENT,
.tox/py/lib/python3.8/site-packages/selenium/webdriver/remote/webelement.py:664: in _execute
    return self._parent.execute(command, params)
.tox/py/lib/python3.8/site-packages/selenium/webdriver/remote/webdriver.py:344: in execute
    self.error_handler.check_response(response)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <selenium.webdriver.remote.errorhandler.ErrorHandler object at 0x7f8c94fb6850>
response = {'status': 400, 'value': '{"value":{"error":"invalid argument","message":"File not found: /home/runner/work/deformdemo...//marionette/content/error.js:310:5\\ninteraction.uploadFiles@chrome://marionette/content/interaction.js:509:13\\n"}}'}

    def check_response(self, response):
        """
        Checks that a JSON response from the WebDriver does not have an error.
    
        :Args:
         - response - The JSON response from the WebDriver server as a dictionary
           object.
    
        :Raises: If the response contains an error message.
        """
        status = response.get('status', None)
        if not status or status == ErrorCode.SUCCESS:
            return
        value = None
        message = response.get("message", "")
        screen = response.get("screen", "")
        stacktrace = None
        if isinstance(status, int):
            value_json = response.get('value', None)
            if value_json and isinstance(value_json, str):
                import json
                try:
                    value = json.loads(value_json)
                    if len(value.keys()) == 1:
                        value = value['value']
                    status = value.get('error', None)
                    if not status:
                        status = value["status"]
                        message = value["value"]
                        if not isinstance(message, str):
                            value = message
                            message = message.get('message')
                    else:
                        message = value.get('message', None)
                except ValueError:
                    pass
    
        if status in ErrorCode.NO_SUCH_ELEMENT:
            exception_class = NoSuchElementException
        elif status in ErrorCode.NO_SUCH_FRAME:
            exception_class = NoSuchFrameException
        elif status in ErrorCode.NO_SUCH_WINDOW:
            exception_class = NoSuchWindowException
        elif status in ErrorCode.STALE_ELEMENT_REFERENCE:
            exception_class = StaleElementReferenceException
        elif status in ErrorCode.ELEMENT_NOT_VISIBLE:
            exception_class = ElementNotVisibleException
        elif status in ErrorCode.INVALID_ELEMENT_STATE:
            exception_class = InvalidElementStateException
        elif status in ErrorCode.INVALID_SELECTOR \
                or status in ErrorCode.INVALID_XPATH_SELECTOR \
                or status in ErrorCode.INVALID_XPATH_SELECTOR_RETURN_TYPER:
            exception_class = InvalidSelectorException
        elif status in ErrorCode.ELEMENT_IS_NOT_SELECTABLE:
            exception_class = ElementNotSelectableException
        elif status in ErrorCode.ELEMENT_NOT_INTERACTABLE:
            exception_class = ElementNotInteractableException
        elif status in ErrorCode.INVALID_COOKIE_DOMAIN:
            exception_class = InvalidCookieDomainException
        elif status in ErrorCode.UNABLE_TO_SET_COOKIE:
            exception_class = UnableToSetCookieException
        elif status in ErrorCode.TIMEOUT:
            exception_class = TimeoutException
        elif status in ErrorCode.SCRIPT_TIMEOUT:
            exception_class = TimeoutException
        elif status in ErrorCode.UNKNOWN_ERROR:
            exception_class = WebDriverException
        elif status in ErrorCode.UNEXPECTED_ALERT_OPEN:
            exception_class = UnexpectedAlertPresentException
        elif status in ErrorCode.NO_ALERT_OPEN:
            exception_class = NoAlertPresentException
        elif status in ErrorCode.IME_NOT_AVAILABLE:
            exception_class = ImeNotAvailableException
        elif status in ErrorCode.IME_ENGINE_ACTIVATION_FAILED:
            exception_class = ImeActivationFailedException
        elif status in ErrorCode.MOVE_TARGET_OUT_OF_BOUNDS:
            exception_class = MoveTargetOutOfBoundsException
        elif status in ErrorCode.JAVASCRIPT_ERROR:
            exception_class = JavascriptException
        elif status in ErrorCode.SESSION_NOT_CREATED:
            exception_class = SessionNotCreatedException
        elif status in ErrorCode.INVALID_ARGUMENT:
            exception_class = InvalidArgumentException
        elif status in ErrorCode.NO_SUCH_COOKIE:
            exception_class = NoSuchCookieException
        elif status in ErrorCode.UNABLE_TO_CAPTURE_SCREEN:
            exception_class = ScreenshotException
        elif status in ErrorCode.ELEMENT_CLICK_INTERCEPTED:
            exception_class = ElementClickInterceptedException
        elif status in ErrorCode.INSECURE_CERTIFICATE:
            exception_class = InsecureCertificateException
        elif status in ErrorCode.INVALID_COORDINATES:
            exception_class = InvalidCoordinatesException
        elif status in ErrorCode.INVALID_SESSION_ID:
            exception_class = InvalidSessionIdException
        elif status in ErrorCode.UNKNOWN_METHOD:
            exception_class = UnknownMethodException
        else:
            exception_class = WebDriverException
        if not value:
            value = response['value']
        if isinstance(value, str):
            raise exception_class(value)
        if message == "" and 'message' in value:
            message = value['message']
    
        screen = None
        if 'screen' in value:
            screen = value['screen']
    
        stacktrace = None
        st_value = value.get('stackTrace') or value.get('stacktrace')
        if st_value:
            if isinstance(st_value, str):
                stacktrace = st_value.split('\n')
            else:
                stacktrace = []
                try:
                    for frame in st_value:
                        line = self._value_or_default(frame, 'lineNumber', '')
                        file = self._value_or_default(frame, 'fileName', '<anonymous>')
                        if line:
                            file = "%s:%s" % (file, line)
                        meth = self._value_or_default(frame, 'methodName', '<anonymous>')
                        if 'className' in frame:
                            meth = "%s.%s" % (frame['className'], meth)
                        msg = "    at %s (%s)"
                        msg = msg % (meth, file)
                        stacktrace.append(msg)
                except TypeError:
                    pass
        if exception_class == UnexpectedAlertPresentException:
            alert_text = None
            if 'data' in value:
                alert_text = value['data'].get('text')
            elif 'alert' in value:
                alert_text = value['alert'].get('text')
            raise exception_class(message, screen, stacktrace, alert_text)
>       raise exception_class(message, screen, stacktrace)
E       selenium.common.exceptions.InvalidArgumentException: Message: File not found: /home/runner/work/deformdemo/deformdemo/deformdemo/test.py
E       Stacktrace:
E       WebDriverError@chrome://marionette/content/error.js:181:5
E       InvalidArgumentError@chrome://marionette/content/error.js:310:5
E       interaction.uploadFiles@chrome://marionette/content/interaction.js:509:13

Environment

OS: Ubuntu 18.04 and 20.04 LTS Browser: Firefox Browser version: Selenium/Firefox Browser Driver version: GeckoDriver 0.29.0 Language Bindings version: Python 3 Selenium Grid version (if applicable): See above

Deform and Deformdemo are open source projects. I am happy to share whatever information may be helpful to isolate the cause.