{"record":{"id":"4a8617fc0b5ccc81","repo":"langchain-ai/langgraph","slug":"node-as-node-has-no-writers","errorCode":null,"errorMessage":"Node {as_node} has no writers","messagePattern":"Node (.+?) has no writers","errorType":"exception","errorClass":"InvalidUpdateError","httpStatus":null,"severity":"error","filePath":"libs/langgraph/langgraph/pregel/main.py","lineNumber":1957,"sourceCode":"            else:\n                for values, as_node, task_id in updates:\n                    if as_node is None:\n                        raise InvalidUpdateError(\n                            \"as_node is required when applying multiple updates\"\n                        )\n                    if as_node not in self.nodes:\n                        raise InvalidUpdateError(f\"Node {as_node} does not exist\")\n\n                    valid_updates.append((as_node, values, task_id))\n\n            run_tasks: list[PregelTaskWrites] = []\n            run_task_ids: list[str] = []\n\n            for as_node, values, provided_task_id in valid_updates:\n                # create task to run all writers of the chosen node\n                writers = self.nodes[as_node].flat_writers\n                if not writers:\n                    raise InvalidUpdateError(f\"Node {as_node} has no writers\")\n                writes: deque[tuple[str, Any]] = deque()\n                task = PregelTaskWrites((), as_node, writes, [INTERRUPT])\n                # get the task ids that were prepared for this node\n                # if a task id was provided in the StateUpdate, we use it\n                # otherwise, we use the next available task id\n                prepared_task_ids = node_to_task_ids.get(as_node, deque())\n                task_id = provided_task_id or (\n                    prepared_task_ids.popleft()\n                    if prepared_task_ids\n                    else str(uuid5(UUID(checkpoint[\"id\"]), INTERRUPT))\n                )\n                run_tasks.append(task)\n                run_task_ids.append(task_id)\n                run = RunnableSequence(*writers) if len(writers) > 1 else writers[0]\n                # execute task\n                run.invoke(\n                    values,\n                    patch_config(","sourceCodeStart":1939,"sourceCodeEnd":1975,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/langgraph/langgraph/pregel/main.py#L1939-L1975","documentation":"Error \"Node {as_node} has no writers\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/langgraph/langgraph/pregel/main.py:1957 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"}