langchain-ai/langgraph · error · ValueError

No checkpointer set

Error message

No checkpointer set

What it means

Error "No checkpointer set" thrown in langchain-ai/langgraph.

Source

Thrown at libs/langgraph/langgraph/pregel/main.py:1402

            patch_checkpoint_map(saved.config, saved.metadata),
            saved.metadata,
            saved.checkpoint["ts"],
            patch_checkpoint_map(saved.parent_config, saved.metadata),
            tasks_with_writes,
            tuple([i for task in tasks_with_writes for i in task.interrupts]),
        )

    def get_state(
        self, config: RunnableConfig, *, subgraphs: bool = False
    ) -> StateSnapshot:
        """Get the current state of the graph."""
        checkpointer: BaseCheckpointSaver | None = ensure_config(config)[CONF].get(
            CONFIG_KEY_CHECKPOINTER, self.checkpointer
        )
        if isinstance(checkpointer, BaseCheckpointSaver):
            checkpointer = self._apply_checkpointer_allowlist(checkpointer)
        if not checkpointer:
            raise ValueError("No checkpointer set")

        if (
            checkpoint_ns := config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
        ) and CONFIG_KEY_CHECKPOINTER not in config[CONF]:
            # remove task_ids from checkpoint_ns
            recast = recast_checkpoint_ns(checkpoint_ns)
            # find the subgraph with the matching name
            for _, pregel in self.get_subgraphs(namespace=recast, recurse=True):
                return pregel.get_state(
                    patch_configurable(config, {CONFIG_KEY_CHECKPOINTER: checkpointer}),
                    subgraphs=subgraphs,
                )
            else:
                raise ValueError(f"Subgraph {recast} not found")

        config = merge_configs(self.config, config) if self.config else config
        if self.checkpointer is True:
            ns = cast(str, config[CONF][CONFIG_KEY_CHECKPOINT_NS])

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/langgraph/langgraph/pregel/main.py:1402 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/d445a21f7a6e618b. Report an issue: GitHub.