Unreal Engine 5.9 Preview 1 is out

Epic Games released Unreal Engine 5.9.0 Preview 1, also called the MegaJam Preview, on November 9, 2026. It is a preview, so it is still changing. Epic recommends testing it on a copy of your project.

The experimental Unreal MCP now starts with the editor. MCP is a way for an AI agent to use tools in the editor. It expands its toolsets, which are groups of those tools, to cover rendering, source control, profiling, debugging, gameplay testing, geometry, audio, UI, and level creation. A new Fab toolset lets agents search the catalog, browse your library, and install free or purchased assets into a project.

There is a known bug, UE-412135: in new projects the toolset plugins are off, including AllToolsets. Before you connect an agent, enable All Toolsets in Edit > Plugins, then restart the editor. You can also add the AllToolsets plugin to the .uproject file.

Primary source: Unreal Engine 5.9 MegaJam Preview. Official notes: Unreal Engine 5.9 Preview release notes.