unclecode/crawl4ai · error · ValueError

Invalid hook type: {hook_type}

Error message

Invalid hook type: {hook_type}

What it means

Error "Invalid hook type: {hook_type}" thrown in unclecode/crawl4ai.

Source

Thrown at crawl4ai/legacy/crawler_strategy.py:165

        # self.service = Service(chromedriver_path)
        # self.service.log_path = "NUL"
        # self.driver = webdriver.Chrome(service=self.service, options=self.options)

        # Use selenium-manager (built into Selenium 4.10.0+)
        self.service = Service()
        self.driver = webdriver.Chrome(options=self.options)

        self.driver = self.execute_hook("on_driver_created", self.driver)

        if kwargs.get("cookies"):
            for cookie in kwargs.get("cookies"):
                self.driver.add_cookie(cookie)

    def set_hook(self, hook_type: str, hook: Callable):
        if hook_type in self.hooks:
            self.hooks[hook_type] = hook
        else:
            raise ValueError(f"Invalid hook type: {hook_type}")

    def execute_hook(self, hook_type: str, *args):
        hook = self.hooks.get(hook_type)
        if hook:
            result = hook(*args)
            if result is not None:
                if isinstance(result, webdriver.Chrome):
                    return result
                else:
                    raise TypeError(
                        f"Hook {hook_type} must return an instance of webdriver.Chrome or None."
                    )
        # If the hook returns None or there is no hook, return self.driver
        return self.driver

    def update_user_agent(self, user_agent: str):
        self.options.add_argument(f"user-agent={user_agent}")
        self.driver.quit()

View on GitHub (pinned to 7e80152142)

Solutions

1. Use one of the supported hook types (e.g. on_driver_created, before_get_url, after_get_url, before_return_html).
2. Check the hook name string for typos.

Example fix

crawler_strategy.set_hook('after_get_url', my_hook)

When it happens

Trigger: Thrown at crawl4ai/legacy/crawler_strategy.py:165 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of unclecode/crawl4ai@7e80152142 (2026-08-14). Data as JSON: /api/errors/1c7a2d3a796981f1. Report an issue: GitHub.