browser-use/browser-use · error · ValueError

{func.__name__}() missing required special parameter '{param

Error message

{func.__name__}() missing required special parameter '{param.name}'

What it means

Error "{func.__name__}() missing required special parameter '{param.name}'" thrown in browser-use/browser-use.

Source

Thrown at browser_use/tools/registry/service.py:225

					# This is a special parameter
					if param.name in kwargs:
						value = kwargs[param.name]
						# Check if required special param is None
						if value is None and param.default == Parameter.empty:
							if param.name == 'browser_session':
								raise ValueError(f'Action {func.__name__} requires browser_session but none provided.')
							elif param.name == 'page_extraction_llm':
								raise ValueError(f'Action {func.__name__} requires page_extraction_llm but none provided.')
							elif param.name == 'file_system':
								raise ValueError(f'Action {func.__name__} requires file_system but none provided.')
							elif param.name == 'page':
								raise ValueError(f'Action {func.__name__} requires page but none provided.')
							elif param.name == 'available_file_paths':
								raise ValueError(f'Action {func.__name__} requires available_file_paths but none provided.')
							elif param.name == 'file_system':
								raise ValueError(f'Action {func.__name__} requires file_system but none provided.')
							else:
								raise ValueError(f"{func.__name__}() missing required special parameter '{param.name}'")
						call_args.append(value)
					elif param.default != Parameter.empty:
						call_args.append(param.default)
					else:
						# Special param is required but not provided
						if param.name == 'browser_session':
							raise ValueError(f'Action {func.__name__} requires browser_session but none provided.')
						elif param.name == 'page_extraction_llm':
							raise ValueError(f'Action {func.__name__} requires page_extraction_llm but none provided.')
						elif param.name == 'file_system':
							raise ValueError(f'Action {func.__name__} requires file_system but none provided.')
						elif param.name == 'page':
							raise ValueError(f'Action {func.__name__} requires page but none provided.')
						elif param.name == 'available_file_paths':
							raise ValueError(f'Action {func.__name__} requires available_file_paths but none provided.')
						elif param.name == 'file_system':
							raise ValueError(f'Action {func.__name__} requires file_system but none provided.')
						else:

View on GitHub (pinned to 6c73fced2f)

Solutions

1. Add the required special parameter to the action signature (e.g., browser_session: BrowserSession).

When it happens

Trigger: A required special (framework-injected) parameter is missing at call time.

Common situations: Registry invoked without the agent context that normally injects special parameters.

AI-assisted analysis of browser-use/browser-use@6c73fced2f (2026-08-14). Data as JSON: /api/errors/1b844207359c7427. Report an issue: GitHub.