{"record":{"id":"ce5d92293f44fe76","repo":"langchain-ai/langgraph","slug":"cannot-apply-multiple-updates-when-updating-as-inp","errorCode":null,"errorMessage":"Cannot apply multiple updates when updating as input","messagePattern":"Cannot apply multiple updates when updating as input","errorType":"exception","errorClass":"InvalidUpdateError","httpStatus":null,"severity":"error","filePath":"libs/langgraph/langgraph/pregel/main.py","lineNumber":1749,"sourceCode":"                    create_checkpoint(checkpoint, channels, step),\n                    {\n                        \"source\": \"update\",\n                        \"step\": step + 1,\n                        \"parents\": saved.metadata.get(\"parents\", {}) if saved else {},\n                    },\n                    get_new_channel_versions(\n                        checkpoint_previous_versions,\n                        checkpoint[\"channel_versions\"],\n                    ),\n                )\n                return patch_checkpoint_map(\n                    next_config, saved.metadata if saved else None\n                )\n\n            # act as an input\n            if as_node == INPUT:\n                if len(updates) > 1:\n                    raise InvalidUpdateError(\n                        \"Cannot apply multiple updates when updating as input\"\n                    )\n\n                if input_writes := deque(map_input(self.input_channels, values)):\n                    apply_writes(\n                        checkpoint,\n                        channels,\n                        [PregelTaskWrites((), INPUT, input_writes, [])],\n                        checkpointer.get_next_version,\n                        self.trigger_to_nodes,\n                    )\n\n                    # apply input write to channels\n                    next_step = (\n                        step + 1\n                        if saved and saved.metadata.get(\"step\") is not None\n                        else -1\n                    )","sourceCodeStart":1731,"sourceCodeEnd":1767,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/langgraph/langgraph/pregel/main.py#L1731-L1767","documentation":"Error \"Cannot apply multiple updates when updating as input\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/langgraph/langgraph/pregel/main.py:1749 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"}