message of type RemoveMessage is not handled in langchain-

[daher928]

Checked other resources

• I added a very descriptive title to this issue.
• I searched the LangChain documentation with the integrated search.
• I used the GitHub search to find a similar question and didn't find it.
• I am sure that this is a bug in LangChain rather than my code.
• The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).

Example Code

from langchain_openai.chat_models.base import _convert_message_to_dict
from langchain_core.messages import RemoveMessage
_convert_message_to_dict(RemoveMessage(id="1"))

Error Message and Stack Trace (if applicable)

Traceback (most recent call last):
  File "/Users/projects/my-chat/main.py", line 23, in <module>
    _convert_message_to_dict(RemoveMessage(id="1"))
  File "/Users/.pyenv/versions/chat/lib/python3.11/site-packages/langchain_openai/chat_models/base.py", line 257, in _convert_message_to_dict
    raise TypeError(f"Got unknown type {message}")
TypeError: Got unknown type content='' additional_kwargs={} response_metadata={} id='1'

Description

In langchain_openai.chat_models.base (and more specifically in langchain_openai.chat_models.base._convert_message_to_dict) there is no handling of messages of type RemoveMessage and it fails over unknown type

System Info

System Information
------------------
> OS:  Darwin
> OS Version:  Darwin Kernel Version 23.6.0: Thu Sep 12 23:35:10 PDT 2024; root:xnu-10063.141.1.701.1~1/RELEASE_ARM64_T6030
> Python Version:  3.11.6 (main, Jun 24 2024, 09:02:31) [Clang 15.0.0 (clang-1500.3.9.4)]

Package Information
-------------------
> langchain_core: 0.3.28
> langchain: 0.3.13
> langchain_community: 0.3.13
> langsmith: 0.2.4
> langchain_experimental: 0.3.4
> langchain_openai: 0.2.14
> langchain_text_splitters: 0.3.4
> langgraph_api: 0.0.15
> langgraph_cli: 0.1.65
> langgraph_license: Installed. No version info available.
> langgraph_platform: Installed. No version info available.
> langgraph_sdk: 0.1.48
> langgraph_storage: Installed. No version info available.

Optional packages not installed
-------------------------------
> langserve

Other Dependencies
------------------
> aiohttp: 3.11.11
> async-timeout: Installed. No version info available.
> click: 8.1.8
> cryptography: 43.0.3
> dataclasses-json: 0.6.7
> httpx: 0.28.1
> httpx-sse: 0.4.0
> jsonpatch: 1.33
> jsonschema-rs: 0.25.1
> langgraph: 0.2.60
> langgraph-checkpoint: 2.0.9
> langsmith-pyo3: Installed. No version info available.
> numpy: 1.26.4
> openai: 1.58.1
> orjson: 3.10.12
> packaging: 24.2
> pydantic: 2.10.4
> pydantic-settings: 2.7.0
> pyjwt: 2.10.1
> python-dotenv: 1.0.1
> PyYAML: 6.0.2
> requests: 2.32.3
> requests-toolbelt: 1.0.0
> SQLAlchemy: 2.0.36
> sse-starlette: 2.1.3
> starlette: 0.41.3
> structlog: 24.4.0
> tenacity: 8.5.0
> tiktoken: 0.8.0
> typing-extensions: 4.12.2
> uvicorn: 0.34.0
> watchfiles: 1.0.3

[daher928]

@hwchase17 Hello Harrison, could you please take a lot at this issue?

[efriis]

Assigning to @vbarda ! I believe the RemoveMessage was intended as a langgraph feature, and we may want to add this as a feature of BaseChatModel to remove this confusion.

I don't think this is a regression (i.e. this always behaved this way). Let me know if that seems right to you!

[daher928]

@efriis It happens when I try to remove messages from graph state in LangGraph and using Azure chat model

I would appreciate fixing it as soon as possible! :)

Thanks!