{"record":{"id":"f89f2a4b466e6107","repo":"langchain-ai/langgraph","slug":"invalid-concurrent-graph-update-f89f2a","errorCode":"INVALID_CONCURRENT_GRAPH_UPDATE","errorMessage":"Can receive only one Overwrite value per super-step.","messagePattern":"Can receive only one Overwrite value per super-step\\.","errorType":"error_code","errorClass":"InvalidUpdateError","httpStatus":null,"severity":"error","filePath":"libs/langgraph/langgraph/channels/delta.py","lineNumber":171,"sourceCode":"            if is_ow:\n                base = _copy.copy(ow_value) if ow_value is not None else self.typ()\n                start = i + 1\n        remaining = values[start:]\n        self.value = self.reducer(base, remaining) if remaining else base\n\n    def update(self, values: Sequence[Any]) -> bool:\n        if not values:\n            return False\n        overwrite_idx: int | None = None\n        for i, v in enumerate(values):\n            is_ow, _ = _get_overwrite(v)\n            if is_ow:\n                if overwrite_idx is not None:\n                    msg = create_error_message(\n                        message=\"Can receive only one Overwrite value per super-step.\",\n                        error_code=ErrorCode.INVALID_CONCURRENT_GRAPH_UPDATE,\n                    )\n                    raise InvalidUpdateError(msg)\n                overwrite_idx = i\n        if overwrite_idx is not None:\n            _, overwrite_value = _get_overwrite(values[overwrite_idx])\n            self.value = (\n                _copy.copy(overwrite_value)\n                if overwrite_value is not None\n                else self.typ()\n            )\n            return True\n        base = self.typ() if self.value is MISSING else self.value\n        self.value = self.reducer(base, list(values))\n        return True\n\n    def get(self) -> Any:\n        if self.value is MISSING:\n            raise EmptyChannelError()\n        return self.value\n","sourceCodeStart":153,"sourceCodeEnd":189,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/langgraph/langgraph/channels/delta.py#L153-L189","documentation":"Error \"Can receive only one Overwrite value per super-step.\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/langgraph/langgraph/channels/delta.py:171 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"}