langchain-ai/langgraph · error · RuntimeError

checkpointer=True cannot be used for root graphs.

Error message

checkpointer=True cannot be used for root graphs.

What it means

Error "checkpointer=True cannot be used for root graphs." thrown in langchain-ai/langgraph.

Source

Thrown at libs/langgraph/langgraph/pregel/main.py:2584

            output_keys = self.stream_channels_asis
        else:
            validate_keys(output_keys, self.channels)
        interrupt_before = interrupt_before or self.interrupt_before_nodes
        interrupt_after = interrupt_after or self.interrupt_after_nodes
        if isinstance(stream_mode, str):
            stream_modes = {stream_mode}
        else:
            stream_modes = set(stream_mode)
        if isinstance(print_mode, str):
            stream_modes.add(print_mode)
        else:
            stream_modes.update(print_mode)
        if self.checkpointer is False:
            checkpointer: BaseCheckpointSaver | None = None
        elif CONFIG_KEY_CHECKPOINTER in config.get(CONF, {}):
            checkpointer = config[CONF][CONFIG_KEY_CHECKPOINTER]
        elif self.checkpointer is True:
            raise RuntimeError("checkpointer=True cannot be used for root graphs.")
        else:
            checkpointer = self.checkpointer
        if isinstance(checkpointer, BaseCheckpointSaver):
            checkpointer = self._apply_checkpointer_allowlist(checkpointer)
        if checkpointer and not config.get(CONF):
            raise ValueError(
                "Checkpointer requires one or more of the following 'configurable' "
                "keys: thread_id, checkpoint_ns, checkpoint_id"
            )
        if CONFIG_KEY_RUNTIME in config.get(CONF, {}):
            store: BaseStore | None = config[CONF][CONFIG_KEY_RUNTIME].store
        else:
            store = self.store
        if CONFIG_KEY_CACHE in config.get(CONF, {}):
            cache: BaseCache | None = config[CONF][CONFIG_KEY_CACHE]
        else:
            cache = self.cache
        if durability is None:

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/langgraph/langgraph/pregel/main.py:2584 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of langchain-ai/langgraph@38031739e5 (2026-08-26). Data as JSON: /api/errors/a4df56b5726ac307. Report an issue: GitHub.