Microsoft's AutoGen entered maintenance mode in October 2025 when its team merged with the Semantic Kernel team to build the unified Microsoft Agent Framework. Critical bug fixes and security patches still ship, new features do not. Existing projects keep running, and Microsoft publishes a migration guide.
That is a smaller story than it sounds, and a bigger one. Smaller because nothing broke. Bigger because AutoGen is where a lot of us learned what a multi-agent system actually is, and it is worth being precise about which parts of that education transfer and which parts were just API surface.
Four ideas transfer.
Conversation History As Shared State
Every component in AutoGen is an agent that sends and receives messages. ConversableAgent, the base class, gives each one a name, a system message that defines its behavior, and configurable capabilities for inference, code execution and human input.
