langgraph checkpoint "thread_id" missing in checkpointer.get_tuple

TL;DR

checkpointer.get_tuple() returns None when the config you pass does not include configurable.thread_id, even when the thread ran fine. The fix is to call it with {"configurable": {"thread_id": "your-thread-id"}} instead of a bare string or an empty dict.

get_tuple returned None: config was missing configurable.thread_id

When to use

• get_tuple returns None but you know the thread ran
• You passed the thread id as a plain string instead of a config dict
• Checkpoint reads fail right after a working invoke or after interrupt()

When not to use

• get_tuple raises a connection error (thats the store, not the config shape)
• Threads are missing because the checkpointer was never persisted (thats storage)
• You want to list all threads (use the checkpointer list method instead)

Steps

1. Call get_tuple with a proper config dict, not a bare string:

config = {"configurable": {"thread_id": "abc-123"}}
state = checkpointer.get_tuple(config)

Expected output: get_tuple returns a CheckpointTuple instead of None. If you were passing just "abc-123", that was the bug.

2. Make sure the thread id matches the one used at invoke time. Thread ids are exact-match:

config = {"configurable": {"thread_id": "abc-123"}}
result = graph.invoke({"input": "..."}, config)

Expected output: the same thread id you pass to invoke is the one you read back. A typo in the id silently returns None.

3. If you use subgraphs, include the checkpoint namespace:

config = {"configurable": {"thread_id": "abc-123", "checkpoint_ns": ""}}

Expected output: reads from the root namespace. Subgraph checkpoints live under their own namespace, so a root-namespace read misses them.

4. Verify the checkpointer actually persisted the write. For SQLite:

import sqlite3
conn = sqlite3.connect("checkpoints.db")
print(conn.execute("select count(*) from checkpoints").fetchone())

Expected output: a nonzero count. Zero rows means nothing was written, so the read side was never the problem.

Variant phrasings

get_tuple returns None after interrupt

Same cause. After interrupt(), resume with the identical config dict, including thread_id.

thread state missing in a subgraph

The subgraph wrote under its own checkpoint_ns. Pass that namespace in the config.

Why it happens

LangGraph keys every checkpoint by thread id, namespace, and checkpoint id. get_tuple builds that key from the config dict; when configurable.thread_id is absent it builds a key that matches nothing and returns None instead of raising. The silent None makes a config-shape mistake look like missing data.

Edge cases

• An in-memory checkpointer loses everything on process restart; None after a restart is expected there, not a bug.
• get_tuple with only thread_id returns the latest checkpoint. Pass checkpoint_id too when you need a specific one.
• Async code must use aget_tuple. The sync call inside a running event loop can hang instead of returning.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstONA8U9WfRiBzPLkYiBogw