Versions and migration
This section documents LangChain 1.x (Python), the split-package layout
(langchain-core, langchain, provider packages such as langchain-openai, and
langchain-community). LangChain released 1.0 in October 2025, replacing its earlier chain and
agent abstractions with a single high-level agent abstraction (originally built in LangGraph, then
moved into langchain).
Most LangChain tutorials and blog posts online still target the 0.x line. Imports like
from langchain.chains import LLMChain look correct but are deprecated — they will run under a
compatibility shim for a time, then stop working. Check the import against the tables below before
trusting an older example.
The 0.x → 1.x split
By mid-2024 LangChain had grown to hundreds of provider integrations living in one package. These
were split out: stable, provider-agnostic abstractions moved to langchain-core; each provider got
its own package (langchain-openai, langchain-anthropic, ...); community-maintained, less stable
integrations moved to langchain-community. See the setup section's package layout page for the
dependency shape this produced.
Deprecated constructs and their replacements
| Deprecated | Replacement |
|---|---|
LLMChain | LCEL: prompt | model | parser |
ConversationChain | MessagesPlaceholder + explicit message history (see the memory section) |
initialize_agent | create_agent (langchain.agents) |
ConversationBufferMemory | Explicit message list management, or a LangGraph checkpointer for durable state |