What causes "Cannot write storage state to {file_path}: {e}" in SeleniumHQ/selenium?

Create the parent directory first: `pathlib.Path(p).parent.mkdir(parents=True, exist_ok=True)`.

SeleniumHQ/selenium · error · OSError

Cannot write storage state to

Error message

Cannot write storage state to {file_path}: {e}

What it means

`storage_state(path=...)` serializes the current browser cookies to JSON. If writing the file raises `OSError` (permission denied, read-only filesystem, missing directory, disk full), Selenium re-raises it as `OSError` with the path and underlying error. The state dict is still returned to the caller even if the write fails after the raise (the raise happens before the return).

Solutions

Create the parent directory first: `pathlib.Path(p).parent.mkdir(parents=True, exist_ok=True)`.
Write to a writable temp location: `tempfile.gettempdir()`.
Check write access: `os.access(pathlib.Path(p).parent, os.W_OK)`.
If you only need the dict, omit `path` and handle serialization yourself.

Example fix

// before
state = api.storage_state(path="out/state.json")  # OSError: dir missing
// after
import pathlib
p = pathlib.Path("out/state.json")
p.parent.mkdir(parents=True, exist_ok=True)
state = api.storage_state(path=str(p))

Defensive patterns

Strategy: validation

Validate before calling

import pathlib, os
p = pathlib.Path("out/state.json")
p.parent.mkdir(parents=True, exist_ok=True)
assert os.access(p.parent, os.W_OK), f"cannot write to {p.parent}"
api.storage_state(path=str(p))

Type guard

import os, pathlib
def storage_state_path_writable(path) -> bool:
    parent = pathlib.Path(path).parent
    return os.access(parent, os.W_OK)

Try / catch

try:
    state = api.storage_state(path=path)
except OSError:
    state = api.storage_state()  # get dict without writing

Prevention

Create the parent directory before writing.
Use a writable temp dir if the target is read-only.
Omit path and serialize the dict yourself if filesystem is uncertain.

When it happens

Trigger: `api.storage_state(path="/readonly/state.json")`, `api.storage_state(path="no/such/dir/state.json")` (parent dir missing), or writing to a full disk. The path's parent directory must exist and be writable.

Common situations: CI artifact directory not created. Writing to a path inside a read-only container layer. Permissions on a shared volume. Disk/quota full.

Related errors

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/a78beb97d3f55a9b. Report an issue: GitHub.

Appendix: source

Thrown at py/selenium/webdriver/common/api_request_context.py:604

    def get_storage_state(self, path: str | pathlib.Path | None = None) -> dict[str, Any]:
        """Export the current browser cookies as a storage state dict.

        Args:
            path: Optional file path to save the storage state as JSON.

        Returns:
            A dict with a "cookies" key containing the browser cookies.
        """
        cookies = self._driver.get_cookies()
        state: dict[str, Any] = {"cookies": cookies}
        if path is not None:
            file_path = pathlib.Path(path)
            try:
                with open(file_path, "w") as f:
                    json.dump(state, f, indent=2)
            except OSError as e:
                raise OSError(f"Cannot write storage state to {file_path}: {e}") from e
        return state

    def _get_cookies_for_request(self, url: str) -> list[dict]:
        """Get matching browser cookies for the request URL."""
        try:
            browser_cookies = self._driver.get_cookies()
        except Exception:
            logger.debug("Could not retrieve browser cookies", exc_info=True)
            return []
        # Derive default domain from the browser's current page for host-only cookies
        default_domain = ""
        try:
            current = self._driver.current_url
            if current:
                default_domain = urllib.parse.urlparse(current).hostname or ""
        except Exception:
            logger.debug("Could not get current URL for host-only cookie matching", exc_info=True)
        return [c for c in browser_cookies if _cookie_matches(c, url, default_domain)]

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