SeleniumHQ/selenium · error · OSError

Path to the extension doesn't exist

Error message

Path to the extension doesn't exist

What it means

`add_extension` checks that the given path resolves to an existing file on disk (after `abspath`/`expanduser` expansion) before queuing it as a `.crx` extension to load. If the file does not exist it raises `OSError`. This guards chromedriver from receiving a missing-file path.

Source

Thrown at py/selenium/webdriver/chromium/options.py:99

        encoded_extensions = []
        for extension in self._extension_files:
            with open(extension, "rb") as f:
                encoded_extensions.append(_decode(f))

        return encoded_extensions + self._extensions

    def add_extension(self, extension: str) -> None:
        """Add the path to an extension to be extracted to ChromeDriver.

        Args:
            extension: Path to the *.crx file.
        """
        if extension:
            extension_to_add = os.path.abspath(os.path.expanduser(extension))
            if os.path.exists(extension_to_add):
                self._extension_files.append(extension_to_add)
            else:
                raise OSError("Path to the extension doesn't exist")
        else:
            raise ValueError("argument can not be null")

    def add_encoded_extension(self, extension: str) -> None:
        """Add Base64-encoded string with extension data to be extracted to ChromeDriver.

        Args:
            extension: Base64 encoded string with extension data.
        """
        if extension:
            self._extensions.append(extension)
        else:
            raise ValueError("argument can not be null")

    @property
    def experimental_options(self) -> dict:
        """Returns a dictionary of experimental options for chromium."""
        return self._experimental_options

View on GitHub (pinned to aa36b38e69)

Solutions

1. Verify the path exists: `if not os.path.exists(path): raise ...` before calling.
2. Use an absolute path resolved against the script location: `pathlib.Path(__file__).parent / "ext.crx"`.
3. If you only have the encoded extension data, use `add_encoded_extension` instead.
4. Check `os.path.isfile(path)` (not just exists) to also catch directory paths.

Example fix

// before
options.add_extension("ext.crx")  # fails if CWD differs
// after
import pathlib
ext = pathlib.Path(__file__).parent / "ext.crx"
options.add_extension(str(ext))

import os
ext = "ext.crx"
if not os.path.isfile(os.path.abspath(os.path.expanduser(ext))):
    raise FileNotFoundError(ext)
options.add_extension(ext)

import os
def is_existing_extension_file(path: str) -> bool:
    return bool(path) and os.path.isfile(os.path.abspath(os.path.expanduser(path)))

try:
    options.add_extension(ext_path)
except OSError:
    # log and either locate the file or use add_encoded_extension
    ...

When it happens

Trigger: `options.add_extension("/wrong/path/ext.crx")`, `options.add_extension("~/notthere.crx")`, relative paths that resolve outside the CWD, or a path to a directory instead of a `.crx` file.

Common situations: Bundling extensions in a CI artifact whose path changed. Relative paths breaking when the script runs from a different working directory. Typos in the path. Downloading a `.crx` that failed.

Related errors

• could not find extension at #{path.inspect}
• argument can not be null
• could not find extension at #{path.inspect}
• Binary Location Must be a String
• could not find extension at #{path.inspect}

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/dffc1f9594c35200. Report an issue: GitHub.