audit-trail-multiple-inheritance-importing-langchain-modules-in-python-3-8-causes-t-d69bc6b9

THEN Upgrade LangChain to version 0.0.250 or later to resolve the multiple inheritance conflict. If upgrade is not possible, manually refactor the HumanMessageChunk class to use composition instead of inheriting from both HumanMessage and BaseMessageChunk.

class HumanMessageChunk(HumanMessage):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._chunk = BaseMessageChunk(*args, **kwargs)
    def __add__(self, other):
        result = super().__add__(other)
        if isinstance(other, BaseMessageChunk):
            result._chunk = self._chunk + other
        return result
    def _merge_kwargs_dict(self, left, right):
        return self._chunk._merge_kwargs_dict(left, right)