LangChain 1.5.0 drops Python 3.10 and adds a model router

LangChain released version 1.5.0 of its open-source toolkit for AI agents. The release removes support for Python 3.10, which has reached end of life. This means that it gets no more updates from the Python team. The lowest Python version is now 3.11. The release also adds a model router, which sends each request to a chosen model.

What changed

The lowest version of the core package, langchain-core, is now 1.8.0. Users on Python 3.10 continue to get langchain 1.4.x. The notes mark the router as beta, which means that it is in test.

The numbers

The notes give no test results, no speed numbers and no size of the change. They list five changes by number and nothing more.

What is not known

The notes do not say how the router picks a model. They do not say if 1.4.x gets repairs. They do not say how many users stay on Python 3.10.

Insight: Old versions can keep known bugs

The new features need Python 3.11. A related case shows the cost of old versions: IBM repaired four bugs in Langflow versions 1.0.0 to 1.12.8, two with a 9.8 CVSS score, in version 1.13.0. This seems to push teams to move up, because a team that stays on Python 3.10 misses the new features. Watch if 1.4.x gets security repairs.