checkpointe-postgres v2.0.23 has error in any exists thread

Question

checkpointe-postgres v2.0.23 has error in any exists thread

Opened this issue 2 months ago · 5 comments

Checked other resources

This is a bug, not a usage question. For questions, please use the LangChain Forum (https://forum.langchain.com/).
I added a clear and detailed title that summarizes the issue.
I read what a minimal reproducible example is (https://stackoverflow.com/help/minimal-reproducible-example).
I included a self-contained, minimal example that demonstrates the issue INCLUDING all the relevant imports. The code run AS IS to reproduce the issue.

Example Code

when continue any exists threads

Error Message and Stack Trace (if applicable)

'NoneType' object is not a mapping\nTraceback (most recent call last):\n  File \"/app/intentkit/core/engine.py\", line 564, in stream_agent\n    async for chunk in executor.astream({\"messages\": messages}, stream_config):\n  File \"/app/.venv/lib/python3.12/site-packages/langgraph/pregel/__init__.py\", line 2710, in astream\n    async with AsyncPregelLoop(\n               ^^^^^^^^^^^^^^^^\n  File \"/app/.venv/lib/python3.12/site-packages/langgraph/pregel/loop.py\", line 1177, in __aenter__\n    saved = await self.checkpointer.aget_tuple(self.checkpoint_config)\n            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/app/.venv/lib/python3.12/site-packages/langgraph/checkpoint/postgres/aio.py\", line 217, in aget_tuple\n    return await self._load_checkpoint_tuple(value)\n           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/app/.venv/lib/python3.12/site-packages/langgraph/checkpoint/postgres/aio.py\", line 413, in _load_checkpoint_tuple\n    \"channel_values\": {\n                      ^\nTypeError: 'NoneType' object is not a mapping\n"

Description

In the new thread, there are no errors, but if you continue any previous version of the thread, this error will occur.

System Info

System Information

OS: Linux
OS Version: #1 SMP PREEMPT_DYNAMIC Tue Apr 8 13:14:54 UTC 2025
Python Version: 3.12.11 (main, Jul 1 2025, 02:44:10) [GCC 12.2.0]

Package Information

langchain_core: 0.3.69
langchain: 0.3.26
langchain_community: 0.3.27
langsmith: 0.4.6
langchain_anthropic: 0.3.17
langchain_mcp_adapters: 0.1.7
langchain_openai: 0.3.28
langchain_postgres: 0.0.15
langchain_text_splitters: 0.3.8
langchain_xai: 0.2.4
langgraph_sdk: 0.1.73

Optional packages not installed

langserve

Other Dependencies

aiohttp<4,>=3.9.1: Installed. No version info available.
aiohttp<4.0.0,>=3.8.3: Installed. No version info available.
anthropic<1,>=0.57.0: Installed. No version info available.
async-timeout<5.0.0,>=4.0.0;: Installed. No version info available.
asyncpg>=0.30.0: Installed. No version info available.
dataclasses-json<0.7,>=0.5.7: Installed. No version info available.
httpx: 0.28.1
httpx-sse<1.0.0,>=0.4.0: Installed. No version info available.
httpx>=0.25.2: Installed. No version info available.
jsonpatch<2.0,>=1.33: Installed. No version info available.
langchain-anthropic;: Installed. No version info available.
langchain-aws;: Installed. No version info available.
langchain-azure-ai;: Installed. No version info available.
langchain-cohere;: Installed. No version info available.
langchain-community;: Installed. No version info available.
langchain-core<0.4,>=0.3.36: Installed. No version info available.
langchain-core<0.4.0,>=0.2.13: Installed. No version info available.
langchain-core<1.0.0,>=0.3.51: Installed. No version info available.
langchain-core<1.0.0,>=0.3.62: Installed. No version info available.
langchain-core<1.0.0,>=0.3.66: Installed. No version info available.
langchain-core<1.0.0,>=0.3.68: Installed. No version info available.
langchain-deepseek;: Installed. No version info available.
langchain-fireworks;: Installed. No version info available.
langchain-google-genai;: Installed. No version info available.
langchain-google-vertexai;: Installed. No version info available.
langchain-groq;: Installed. No version info available.
langchain-huggingface;: Installed. No version info available.
langchain-mistralai;: Installed. No version info available.
langchain-ollama;: Installed. No version info available.
langchain-openai;: Installed. No version info available.
langchain-openai<0.4,>=0.3.18: Installed. No version info available.
langchain-perplexity;: Installed. No version info available.
langchain-text-splitters<1.0.0,>=0.3.8: Installed. No version info available.
langchain-together;: Installed. No version info available.
langchain-xai;: Installed. No version info available.
langchain<1.0.0,>=0.3.26: Installed. No version info available.
langsmith-pyo3: Installed. No version info available.
langsmith>=0.1.125: Installed. No version info available.
langsmith>=0.1.17: Installed. No version info available.
langsmith>=0.3.45: Installed. No version info available.
mcp>=1.9.2: Installed. No version info available.
numpy<3,>=1.21: Installed. No version info available.
numpy>=1.26.2;: Installed. No version info available.
numpy>=2.1.0;: Installed. No version info available.
openai-agents: Installed. No version info available.
openai<2.0.0,>=1.86.0: Installed. No version info available.
opentelemetry-api: Installed. No version info available.
opentelemetry-exporter-otlp-proto-http: Installed. No version info available.
opentelemetry-sdk: Installed. No version info available.
orjson: 3.11.0
orjson>=3.10.1: Installed. No version info available.
packaging: 24.2
packaging>=23.2: Installed. No version info available.
pgvector<0.4,>=0.2.5: Installed. No version info available.
psycopg-pool<4,>=3.2.1: Installed. No version info available.
psycopg<4,>=3: Installed. No version info available.
pydantic: 2.10.6
pydantic-settings<3.0.0,>=2.4.0: Installed. No version info available.
pydantic<3.0.0,>=2.7.4: Installed. No version info available.
pydantic>=2.7.4: Installed. No version info available.
pytest: Installed. No version info available.
PyYAML>=5.3: Installed. No version info available.
requests: 2.32.3
requests-toolbelt: 1.0.0
requests<3,>=2: Installed. No version info available.
rich: Installed. No version info available.
SQLAlchemy<3,>=1.4: Installed. No version info available.
sqlalchemy<3,>=2: Installed. No version info available.
tenacity!=8.4.0,<10,>=8.1.0: Installed. No version info available.
tenacity!=8.4.0,<10.0.0,>=8.1.0: Installed. No version info available.
tiktoken<1,>=0.7: Installed. No version info available.
typing-extensions>=4.7: Installed. No version info available.
zstandard: 0.23.0

Answer 1 · 2025-07-17T09:13:17.000Z

I'm experiencing the same issue when calling checkpointer.list(config=None, filter= {"user_id":user_id}) and basically any other usage of the PostgresSaver checkpointer. This has broken my application. Same message:
'NoneType' object is not a mapping

Reverting back to version 2.0.22 solved it for me.

Answer 2 · 2025-07-17T10:23:27.000Z

I’m encountering the same error. Downgrading to version 2.0.21 resolves the issue.

File "/app/.venv/lib/python3.12/site-packages/langgraph/checkpoint/postgres/aio.py", line 280, in aput
    await cur.execute(
  File "/app/.venv/lib/python3.12/site-packages/psycopg/cursor_async.py", line 93, in execute
    await self._conn.wait(
  File "/app/.venv/lib/python3.12/site-packages/psycopg/connection_async.py", line 439, in wait
    return await waiting.wait_async(gen, self.pgconn.socket, interval=interval)

...

File "/app/.venv/lib/python3.12/site-packages/psycopg/types/json.py", line 149, in dump
    if isinstance((data := dumps(obj)), str):
                           ^^^^^^^^^^
  File "/usr/local/lib/python3.12/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/json/encoder.py", line 200, in encode
    chunks = self.iterencode(o, _one_shot=True)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/json/encoder.py", line 258, in iterencode
    return _iterencode(o, 0)
           ^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/json/encoder.py", line 180, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type HumanMessage is not JSON serializable
During task with name 'a1f49e69-3ef1-4023-9bd1-780d3aff455f' and id 'ab9e6d92-6e46-8bfb-2d9f-8f048dce5da8'

The error occurs in langgraph/checkpoint/postgres/aio.py within the aput function, specifically in the part where the checkpoint is being saved:

Original code (2.0.21):

await cur.execute(
    self.UPSERT_CHECKPOINTS_SQL,
    (
        thread_id,
        checkpoint_ns,
        checkpoint["id"],
        checkpoint_id,
        Jsonb(self._dump_checkpoint(copy)),
        self._dump_metadata(get_checkpoint_metadata(config, metadata)),
    ),
)

Modified code(2.0.23):

await cur.execute(
    self.UPSERT_CHECKPOINTS_SQL,
    (
        thread_id,
        checkpoint_ns,
        checkpoint["id"],
        checkpoint_id,
        Jsonb(copy),
        Jsonb(get_checkpoint_metadata(config, metadata)),
    ),
)

The error is triggered in the modified version due to an attempt to serialize a HumanMessage object, which is not JSON serializable.

Answer 3 · 2025-07-17T13:58:46.000Z

🤖 Open SWE has been triggered for this issue. Processing...

View run in Open SWE here (this URL will only work for @eyurtsev)

Dev Metadata

{ "runId": "1f063162-7ee8-67a1-b4c3-e839873fd85b", "threadId": "fac1e127-762d-4550-8284-6f274eb63968" }

Answer 4 · 2025-07-22T10:10:58.000Z

Same issue here, I comment, so I get an update when the issue is resolved. =D

Answer 5 · 2025-08-28T15:38:57.000Z

This breaks all checkpointing. Will it be fixed?