SeleniumHQ/selenium · error · TypeError

Not allowed to specify a version when using an existing serv

Error message

Not allowed to specify a version when using an existing server path

What it means

Raised as TypeError by the Server constructor when both path and version are specified simultaneously. The path parameter points to an existing server .jar, making the version parameter (used to download a specific server version) contradictory and ambiguous. The constructor enforces mutual exclusivity at the top before any other field is set.

Source

Thrown at py/selenium/webdriver/remote/server.py:67

            pin drivers with "--driver-configuration").
    """

    DEFAULT_ARGS = ("--selenium-manager", "true", "--enable-managed-downloads", "true")

    def __init__(
        self,
        host=None,
        port=4444,
        path=None,
        version=None,
        log_level="INFO",
        env=None,
        java_path=None,
        startup_timeout=10,
        args=None,
    ):
        if path and version:
            raise TypeError("Not allowed to specify a version when using an existing server path")

        self.host = host
        self.port = port
        self.path = path
        self.version = version
        self.log_level = log_level
        self.env = env
        self.java_path = java_path
        self.startup_timeout = startup_timeout
        self.args = list(args) if args is not None else list(self.DEFAULT_ARGS)
        self.process = None

    @property
    def startup_timeout(self):
        return self._startup_timeout

    @startup_timeout.setter
    def startup_timeout(self, timeout):

View on GitHub (pinned to aa36b38e69)

Solutions

If using a local jar, remove the version parameter: Server(path='/path/to/selenium-server.jar')
If downloading a specific version, remove the path parameter: Server(version='4.20.0')
Ensure your configuration sets only one of the two, not both

Example fix

// before
server = Server(path='/opt/selenium-server.jar', version='4.20.0')

// after
server = Server(path='/opt/selenium-server.jar')

Defensive patterns

Strategy: validation

Validate before calling

path = '/opt/selenium-server.jar'
version = '4.20.0'
if path and version:
    version = None  # path takes priority
server = Server(path=path, version=version)

Try / catch

try:
    server = Server(path=path, version=version)
except TypeError:
    server = Server(path=path)  # drop version when path is given

Prevention

Provide only one of path or version, never both
Use path when you have a local jar, version when you want a download
Clean up config files that may set both fields

When it happens

Trigger: Calling Server(path='/path/to/selenium-server.jar', version='4.20.0') triggers the TypeError. Providing both means the library cannot determine whether to use the local jar or download a specific version.

Common situations: Copy-pasting from examples that use version= and adding a path= override without removing version=. Config files that set both fields.

Related errors

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/6c28b627aef3dc56. Report an issue: GitHub.