unclecode/crawl4ai · error · NotImplementedError

Browser type {self.browser_type} not supported

Error message

Browser type {self.browser_type} not supported

What it means

While building subprocess launch flags (_get_browser_args / managed browser path), BrowserManager supports only 'chromium' (and 'firefox' with its own flag set); any other browser_type string reaches the else branch and raises NotImplementedError. This constrains the managed-browser (CDP subprocess) path — Playwright's own launch API supports more types, but this manager does not.

Source

Thrown at crawl4ai/browser_manager.py:406

            ]
            if self.headless:
                flags.append("--headless=new")
            # Add viewport flag if specified in config
            if self.browser_config.viewport_height and self.browser_config.viewport_width:
                flags.append(f"--window-size={self.browser_config.viewport_width},{self.browser_config.viewport_height}")
            # merge common launch flags
            flags.extend(self.build_browser_flags(self.browser_config))
        elif self.browser_type == "firefox":
            flags = [
                "--remote-debugging-port",
                str(self.debugging_port),
                "--profile",
                self.user_data_dir,
            ]
            if self.headless:
                flags.append("--headless")
        else:
            raise NotImplementedError(f"Browser type {self.browser_type} not supported")
        return base + flags

    async def cleanup(self):
        """Cleanup browser process and temporary directory"""
        # Set shutting_down flag BEFORE any termination actions
        self.shutting_down = True

        if self.browser_process:
            try:
                # For builtin browsers that should persist, we should check if it's a detached process
                # Only terminate if we have proper control over the process
                if not self.browser_process.poll():
                    # Process is still running
                    self.browser_process.terminate()
                    # Wait for process to end gracefully
                    for _ in range(10):  # 10 attempts, 100ms each
                        if self.browser_process.poll() is not None:
                            break

View on GitHub (pinned to 7e80152142)

Solutions

1. Use browser_type='chromium' (default) or 'firefox' when use_managed_browser=True.
2. For webkit or other engines, disable the managed browser: BrowserConfig(use_managed_browser=False) and let Playwright's standard launch handle it.
3. Check spelling/casing of browser_type against the supported set.

Example fix

# before
BrowserConfig(browser_type='webkit', use_managed_browser=True)  # NotImplementedError

# after
BrowserConfig(browser_type='webkit', use_managed_browser=False)

MANAGED_SUPPORTED = {'chromium', 'firefox'}
if cfg.get('use_managed_browser') and cfg['browser_type'] not in MANAGED_SUPPORTED:
    raise ValueError(f"managed browser supports only {MANAGED_SUPPORTED}, got {cfg['browser_type']}")

def supports_managed_browser(browser_type: str) -> bool:
    return browser_type in {"chromium", "firefox"}

try:
    browser_config = BrowserConfig(browser_type=bt, use_managed_browser=True)
except NotImplementedError:
    browser_config = BrowserConfig(browser_type=bt, use_managed_browser=False)

When it happens

Trigger: BrowserConfig(browser_type='webkit') combined with use_managed_browser=True; browser_type='chrome' or 'edge' (wrong identifier); typos like 'Chromium' (case-sensitive in this branch).

Common situations: Assuming any Playwright browser works with the managed CDP mode; porting configs from Playwright where browser_type strings differ; using branded names ('chrome') instead of engine names.

Related errors

• Container not found: ${config.container_selector}
• Timeout after {timeout}ms waiting for selector '{wait_for}'
• [NSTProxy] token and channel_id are required
• [NSTProxy] Invalid protocol: {protocol}
• concurrency must be positive

AI-assisted analysis of unclecode/crawl4ai@7e80152142 (2026-08-14). Data as JSON: /api/errors/86e614b2e190f221. Report an issue: GitHub.