[🐛 Bug]: [py] Launching WPE WebKit fails

[cgoldberg]

What happened?

Using the Python bindings, the WPE WebKit browser functionality seems totally broken. Trying to instantiate webdriver.WPEWebKit() results in:

selenium.common.exceptions.InvalidArgumentException: Message: Invalid alwaysMatch capabilities

(Note: WPE WebKit is only available on Linux)

How can we reproduce the issue?

Run the following code:


from selenium import webdriver

driver = webdriver.WPEWebKit()


(Make sure WPE WebKit is installed. On Debian/Ubuntu, install with `sudo apt install wpewebkit-driver`)

Relevant log output

DEBUG:selenium.webdriver.common.driver_finder:Skipping Selenium Manager; path to MiniBrowser driver specified in Service class: /usr/bin/WPEWebDriver
DEBUG:selenium.webdriver.common.service:Started executable: `/usr/bin/WPEWebDriver` in a child process with pid: 20817 using 0 to output -3
DEBUG:selenium.webdriver.remote.remote_connection:POST http://localhost:56037/session {'capabilities': {'firstMatch': [{}], 'alwaysMatch': {'browserName': 'MiniBrowser', 'pageLoadStrategy': <PageLoadStrategy.normal: 'normal'>, 'wpe:browserOptions': {}}}}
DEBUG:urllib3.connectionpool:Starting new HTTP connection (1): localhost:56037
DEBUG:urllib3.connectionpool:http://localhost:56037 "POST /session HTTP/1.1" 400 0
DEBUG:selenium.webdriver.remote.remote_connection:Remote response: status=400 | data={"value":{"error":"invalid argument","message":"Invalid alwaysMatch capabilities","stacktrace":""}} | headers=HTTPHeaderDict({'Server': 'WebKitWebDriver', 'Date': 'Tue, 01 Apr 2025 01:09:00 GMT', 'Content-Type': 'application/json; charset=utf-8', 'Cache-Control': 'no-cache', 'Content-Length': '99'})
DEBUG:selenium.webdriver.remote.remote_connection:Finished Request
Traceback (most recent call last):
  File "/home/cgoldberg617/code/selenium/py/sel.py", line 13, in <module>
    driver = webdriver.WPEWebKit()
  File "/home/cgoldberg617/code/selenium/py/selenium/webdriver/wpewebkit/webdriver.py", line 49, in __init__
    super().__init__(command_executor=self.service.service_url, options=options)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/cgoldberg617/code/selenium/py/selenium/webdriver/remote/webdriver.py", line 250, in __init__
    self.start_session(capabilities)
    ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/home/cgoldberg617/code/selenium/py/selenium/webdriver/remote/webdriver.py", line 342, in start_session
    response = self.execute(Command.NEW_SESSION, caps)["value"]
               ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/cgoldberg617/code/selenium/py/selenium/webdriver/remote/webdriver.py", line 429, in execute
    self.error_handler.check_response(response)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/home/cgoldberg617/code/selenium/py/selenium/webdriver/remote/errorhandler.py", line 232, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.InvalidArgumentException: Message: Invalid alwaysMatch capabilities

Operating System

Linux (Debian Stable)

Selenium version

4.30

What are the browser(s) and version(s) where you see this issue?

WPE WebKit

What are the browser driver(s) and version(s) where you see this issue?

wpewebkit-driver 2.38.6-1 (installed from Debian Stable Apt repo)

Are you using Selenium Grid?

No