browser-use/browser-use · error · ValueError

Action {func.__name__} requires browser_session but none pro

Error message

Action {func.__name__} requires browser_session but none provided.

What it means

Error "Action {func.__name__} requires browser_session but none provided." thrown in browser-use/browser-use.

Source

Thrown at browser_use/tools/registry/service.py:213

					if action_kwargs:
						# Use the param_model which has the correct types defined
						params = param_model(**action_kwargs)

			# Build call_args by iterating through original function parameters in order
			params_dict = params.model_dump() if params is not None else {}

			for i, param in enumerate(parameters):
				# Skip first param for Type 1 pattern (it's the model itself)
				if param_model_provided and i == 0 and param.name not in special_param_names:
					call_args.append(params)
				elif param.name in special_param_names:
					# 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':

View on GitHub (pinned to 6c73fced2f)

Solutions

1. Provide a browser_session to the Tools/Agent so the action can run.

When it happens

Trigger: Action declares a browser_session parameter but none was injected by the registry.

Common situations: Using a Tools registry without an attached BrowserSession, or action run outside an Agent.

AI-assisted analysis of browser-use/browser-use@6c73fced2f (2026-08-14). Data as JSON: /api/errors/7d5ce277ffa71771. Report an issue: GitHub.