{"record":{"id":"2d87cd9c27274192","repo":"langchain-ai/langgraph","slug":"sync-run-start-gate-timeout","errorCode":null,"errorMessage":"Sync run.start gate timeout.","messagePattern":"Sync run\\.start gate timeout\\.","errorType":"exception","errorClass":"TimeoutError","httpStatus":null,"severity":"error","filePath":"libs/sdk-py/langgraph_sdk/stream/sync_controller.py","lineNumber":123,"sourceCode":"\n    def signal_paused(self) -> None:\n        \"\"\"Wake every active subscription iterator on interrupt (run pause).\n\n        Pushes the terminal sentinel (`None`) into every subscription queue.\n        Iterators see `None` and return; the shared SSE keeps running so\n        re-iteration after `run.respond(...)` registers a fresh subscription\n        and resumes.\n        \"\"\"\n        with self._lock:\n            subs = list(self._subscriptions.values())\n        for sub in subs:\n            sub.queue.put(None)\n\n    def reconcile_stream(self, candidate_filter: SubscribeParams) -> None:\n        if self._run_start_gate is not None and not self._run_start_gate.wait(\n            timeout=self._run_start_timeout\n        ):\n            raise TimeoutError(\"Sync run.start gate timeout.\")\n        with self._lock:\n            if (\n                self._shared_stream is not None\n                and self._shared_stream_filter is not None\n                and filter_covers(self._shared_stream_filter, dict(candidate_filter))\n            ):\n                return\n            new_filter = self._compute_current_union(extra=candidate_filter)\n            old_stream = self._shared_stream\n            self._shared_stream = self._transport.open_event_stream(\n                self._filter_with_since(new_filter)\n            )\n            self._shared_stream_filter = new_filter\n            if old_stream is not None:\n                drain_thread = threading.Thread(\n                    target=self._drain_and_close,\n                    args=(old_stream,),\n                    daemon=True,","sourceCodeStart":105,"sourceCodeEnd":141,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/sdk-py/langgraph_sdk/stream/sync_controller.py#L105-L141","documentation":"Error \"Sync run.start gate timeout.\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/sdk-py/langgraph_sdk/stream/sync_controller.py:123 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"38031739e551638e373fb553453256c23feeb41f","analyzedAt":"2026-08-26T18:02:49.312Z","schemaVersion":2},"datasetVersion":"2026-08-26T21:11:00.512Z"}