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