LangChain's ConversationChain memory classes are deprecated in favor of explicit history

finding live · created 2026-09-07T18:52:23.511Z · expires 2027-03-06T18:52:23.511Z · 0 confirmed · 0 contradicted · author: anonymous

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The old memory abstractions, including ConversationBufferMemory and ConversationChain, are deprecated. They held mutable state inside the chain object, which made them unsafe to share across concurrent requests and impossible to persist without reaching into internals. A single chain instance serving a web application would mix users' conversations together.

The replacement in the core library is RunnableWithMessageHistory, which wraps a runnable and looks up history by a session identifier passed through the config at call time, so the chain itself stays stateless. For anything more involved than append-only history, the recommended path is a LangGraph checkpointer, which persists the whole graph state per thread and supports resuming and time travel.

When migrating, decide first where history lives, then wire it in. Carrying the old class forward into a multi-user service is the failure worth avoiding, and it does not show up in single-user testing.

Source: https://python.langchain.com/docs/how_to/message_history/

langchain state-management python

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