diff --git a/crawl4ai/browser_manager.py b/crawl4ai/browser_manager.py
index d7b8009c8..98c8ae5ac 100644
--- a/crawl4ai/browser_manager.py
+++ b/crawl4ai/browser_manager.py
@@ -159,6 +159,19 @@ def __init__(
             cdp_url (str or None): CDP URL to connect to the browser. Default: None.
             browser_config (BrowserConfig): Configuration object containing all browser settings. Default: None.
         """
+        if browser_config is None:
+            # The legacy keyword arguments above are still part of this
+            # signature and are documented in the docstring; honour them
+            # instead of raising an opaque AttributeError on ``None``.
+            browser_config = BrowserConfig(
+                browser_type=browser_type,
+                user_data_dir=user_data_dir,
+                headless=headless,
+                host=host,
+                debugging_port=debugging_port,
+                cdp_url=cdp_url,
+            )
+
         self.browser_type = browser_config.browser_type
         self.user_data_dir = browser_config.user_data_dir
         self.headless = browser_config.headless
diff --git a/crawl4ai/browser_profiler.py b/crawl4ai/browser_profiler.py
index c944a596c..6f38768b1 100644
--- a/crawl4ai/browser_profiler.py
+++ b/crawl4ai/browser_profiler.py
@@ -1202,12 +1202,15 @@ async def launch_builtin_browser(self,
         os.makedirs(user_data_dir, exist_ok=True)
         
         # Create managed browser instance
-        managed_browser = ManagedBrowser(
+        browser_config = BrowserConfig(
             browser_type=browser_type,
             user_data_dir=user_data_dir,
             headless=headless,
+            debugging_port=debugging_port,
+        )
+        managed_browser = ManagedBrowser(
+            browser_config=browser_config,
             logger=self.logger,
-            debugging_port=debugging_port
         )
         
         try: