langchain error on Ubuntu 20.04 (python 3.9)

[lightonh]

Traceback (most recent call last):
File "/home/lightonh/NeMo-Guardrails/examples/demo_chain_as_action.py", line 76, in
demo()
File "/home/lightonh/NeMo-Guardrails/examples/demo_chain_as_action.py", line 71, in demo
result = app.generate(messages=history)
File "/home/lightonh/NeMo-Guardrails/nemoguardrails/rails/llm/llmrails.py", line 162, in generate
return asyncio.run(self.generate_async(prompt=prompt, messages=messages))
File "/usr/lib/python3.9/asyncio/runners.py", line 44, in run
return loop.run_until_complete(main)
File "/usr/lib/python3.9/asyncio/base_events.py", line 647, in run_until_complete
return future.result()
File "/home/lightonh/NeMo-Guardrails/nemoguardrails/rails/llm/llmrails.py", line 121, in generate_async
new_events = await self.runtime.generate_events(events)
File "/home/lightonh/NeMo-Guardrails/nemoguardrails/flows/runtime.py", line 144, in generate_events
next_events = await self._process_start_action(events)
File "/home/lightonh/NeMo-Guardrails/nemoguardrails/flows/runtime.py", line 251, in _process_start_action
parameters = inspect.signature(fn).parameters
File "/usr/lib/python3.9/inspect.py", line 3113, in signature
return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
File "/usr/lib/python3.9/inspect.py", line 2862, in from_callable
return _signature_from_callable(obj, sigcls=cls,
File "/usr/lib/python3.9/inspect.py", line 2328, in _signature_from_callable
if _signature_is_builtin(obj):
File "/usr/lib/python3.9/inspect.py", line 1875, in _signature_is_builtin
obj in (type, object))
File "pydantic/main.py", line 911, in pydantic.main.BaseModel.eq
File "/home/lightonh/.virtualenvs/NeMo-Guardrails/lib/python3.9/site-packages/langchain/chains/base.py", line 249, in dict
_dict["_type"] = self._chain_type
File "/home/lightonh/.virtualenvs/NeMo-Guardrails/lib/python3.9/site-packages/langchain/chains/base.py", line 38, in _chain_type
raise NotImplementedError("Saving not supported for this chain type.")
NotImplementedError: Saving not supported for this chain type.

[lightonh]

Package Version

---

aiohttp 3.8.4
aiosignal 1.3.1
annoy 1.17.1
anyio 3.6.2
astroid 2.15.4
async-timeout 4.0.2
attrs 23.1.0
black 23.3.0
certifi 2022.12.7
cfgv 3.3.1
charset-normalizer 3.1.0
click 8.1.3
cmake 3.26.3
dataclasses-json 0.5.7
dill 0.3.6
distlib 0.3.6
exceptiongroup 1.1.1
fastapi 0.95.0
filelock 3.12.0
frozenlist 1.3.3
fsspec 2023.4.0
greenlet 2.0.2
h11 0.14.0
httpcore 0.16.3
httpx 0.23.3
huggingface-hub 0.14.1
identify 2.5.23
idna 3.4
iniconfig 2.0.0
isort 5.12.0
Jinja2 3.1.2
joblib 1.2.0
langchain 0.0.137
lazy-object-proxy 1.9.0
lit 16.0.2
MarkupSafe 2.1.2
marshmallow 3.19.0
marshmallow-enum 1.5.1
mccabe 0.7.0
mpmath 1.3.0
multidict 6.0.4
mypy 1.1.1
mypy-extensions 1.0.0
networkx 3.1
nltk 3.8.1
nodeenv 1.7.0
numpy 1.24.3
nvidia-cublas-cu11 11.10.3.66
nvidia-cuda-cupti-cu11 11.7.101
nvidia-cuda-nvrtc-cu11 11.7.99
nvidia-cuda-runtime-cu11 11.7.99
nvidia-cudnn-cu11 8.5.0.96
nvidia-cufft-cu11 10.9.0.58
nvidia-curand-cu11 10.2.10.91
nvidia-cusolver-cu11 11.4.0.1
nvidia-cusparse-cu11 11.7.4.91
nvidia-nccl-cu11 2.14.3
nvidia-nvtx-cu11 11.7.91
openai 0.27.4
openapi-schema-pydantic 1.2.4
packaging 23.1
pathspec 0.11.1
Pillow 9.5.0
pip 23.1.1
platformdirs 3.3.0
pluggy 1.0.0
pre-commit 3.1.1
pydantic 1.10.6
pylint 2.17.0
pytest 7.2.2
pytest-asyncio 0.21.0
PyYAML 6.0
regex 2023.3.23
requests 2.28.2
rfc3986 1.5.0
scikit-learn 1.2.2
scipy 1.10.1
sentence-transformers 2.2.2
sentencepiece 0.1.98
setuptools 65.5.1
simpleeval 0.9.13
sniffio 1.3.0
SQLAlchemy 1.4.47
starlette 0.26.1
sympy 1.11.1
tenacity 8.2.2
threadpoolctl 3.1.0
tokenizers 0.13.3
tomli 2.0.1
tomlkit 0.11.7
torch 2.0.0
torchvision 0.15.1
tqdm 4.65.0
transformers 4.28.1
triton 2.0.0
typer 0.7.0
typing_extensions 4.5.0
typing-inspect 0.8.0
urllib3 1.26.15
uvicorn 0.21.1
virtualenv 20.22.0
wheel 0.37.1
wrapt 1.15.0
yarl 1.9.2

[aptlin]

Can reproduce with LangChain 0.0.137 and 0.0.149 (latest). Looks like a bug with chain serialization, since demos work if we do not make the _chain_type property abstract (e.g. by just changing this line to return 'default' instead).

cc @hwchase17

[drazvan]

Thanks for reporting this @lightonh and @aptlin. Just pushed a fix for this. We will release a patch version on PyPI very soon as well.

[PetreanuAndi]

This keeps happening.
langchain 0.0.161
trying to run your "demo_chain_as_action.py", nothing else changed.

[Kamalabot]

@drazvan Tried it with langchain 0.0.174 the below error continues to occur.
Tried the fix suggested by @aptlin, it is not working.

[drazvan]

Just to confirm, are you using the main branch from GitHub or the package from PyPI (we haven't yet pushed the fix; we'll push a new version at the end of the month)?

[Kamalabot]

Using the pypi package, not the main branch. Will try the main branch and see how it goes.

[Willis75]

Using the pypi package, not the main branch. Will try the main branch and see how it goes.

Hello, did it work?