{"record":{"id":"528d8f42d64ec9a9","repo":"microsoft/autogen","slug":"mcpworkbench-is-not-started-call-start-first","errorCode":null,"errorMessage":"McpWorkbench is not started. Call start() first.","messagePattern":"McpWorkbench is not started\\. Call start\\(\\) first\\.","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"python/packages/autogen-ext/src/autogen_ext/tools/mcp/_workbench.py","lineNumber":482,"sourceCode":"                UserWarning,\n                stacklevel=2,\n            )\n            return  # Already initialized, no need to start again\n\n        if isinstance(self._server_params, (StdioServerParams, SseServerParams, StreamableHttpServerParams)):\n            self._actor = McpSessionActor(self._server_params, host=self._host)\n            await self._actor.initialize()\n            self._actor_loop = asyncio.get_event_loop()\n        else:\n            raise ValueError(f\"Unsupported server params type: {type(self._server_params)}\")\n\n    async def stop(self) -> None:\n        if self._actor:\n            # Close the actor\n            await self._actor.close()\n            self._actor = None\n        else:\n            raise RuntimeError(\"McpWorkbench is not started. Call start() first.\")\n\n    async def reset(self) -> None:\n        pass\n\n    async def save_state(self) -> Mapping[str, Any]:\n        return McpWorkbenchState().model_dump()\n\n    async def load_state(self, state: Mapping[str, Any]) -> None:\n        pass\n\n    def _to_config(self) -> McpWorkbenchConfig:\n        host_config = self._host.dump_component() if self._host else None\n        return McpWorkbenchConfig(\n            server_params=self._server_params, tool_overrides=self._tool_overrides, host=host_config\n        )\n\n    @classmethod\n    def _from_config(cls, config: McpWorkbenchConfig) -> Self:","sourceCodeStart":464,"sourceCodeEnd":500,"githubUrl":"https://github.com/microsoft/autogen/blob/027ecf0a379bcc1d09956d46d12d44a3ad9cee14/python/packages/autogen-ext/src/autogen_ext/tools/mcp/_workbench.py#L464-L500","documentation":"Error \"McpWorkbench is not started. Call start() first.\" thrown in microsoft/autogen.","triggerScenarios":"Thrown at python/packages/autogen-ext/src/autogen_ext/tools/mcp/_workbench.py:482 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Call start() first"],"exampleFix":"await workbench.start()","handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"027ecf0a379bcc1d09956d46d12d44a3ad9cee14","analyzedAt":"2026-08-15T03:38:00.719Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}