Breaking changes log

Heads-up Unity · 2026-10-05

Unity 7.0 public Alpha has started

Unity opened a public Alpha for Unity 7.0 with builds shipping twice a week. Earlier messaging described a December beta; the Alpha is the first public step. Unity says Unity 7 is a direct continuation of Unity 6, with some breaking changes (obsolete APIs becoming errors, packages moving into the engine, platform minimums moving) but nothing that forces a project rebuild.

What to do: Keep production projects on Unity 6. If you want to test an MCP bridge on Unity 7 alpha, do it in a throwaway project and check the tool's issue tracker first. None of the tools we track claim Unity 7 support yet.

Sources: Unity 7.0 Alpha announcement (Unity Discussions) · Unity 7 FAQ

Breaking change Unity · 2026-09-03

MCP Unity 1.5.0: token authentication required, add_package off by default

Release 1.5.0 fixed a cross-site WebSocket hijacking issue. Every bridge connection must now authenticate with a per-project token, browser-origin handshakes are rejected, and the add_package tool is disabled unless you opt in. The release notes call it a breaking security migration: 1.4.x Node bridges and unauthenticated direct WebSocket clients can no longer connect.

What to do: Upgrade both the Unity package and the Node server together, regenerate your MCP client config from the Unity window, and restart every MCP client process. If you wrote a direct WebSocket client, send the token as HTTP Basic credentials and drop the Origin header.

Tools to check: MCP Unity (CoderGamester)

Sources: mcp-unity releases

News Unity · 2026-07-21

Unity 7 roadmap: December beta, Q1 2027 release, free MCP promised

At Unite Seoul Unity announced Unity 7, built on a CoreCLR runtime. The plan: early Beta in December 2026 and full release in Q1 2027. Unity also said a free-to-use MCP will connect coding agents directly to Unity, and a new CLI and public API will let people work without full Editor access.

What to do: Nothing to do yet. Watch for how the promised MCP relates to the current Unity CLI MCP mode.

Tools to check: Unity CLI (official, with MCP mode and skills)

Sources: Unity 7 Roadmap Revealed at Unite Seoul · GamesBeat coverage

Heads-up Unreal Engine · 2026-06-23

Unreal Engine 5.8 ships with an Experimental official MCP plugin

UE 5.8 includes an Experimental MCP plugin (shown as 'Unreal MCP' in the Plugin Browser, plugin id ModelContextProtocol). It embeds a local MCP server in the editor, defaulting to http://127.0.0.1:8000/mcp. Epic says features may be incomplete and APIs and data formats may change. Third-party summaries of Epic's docs add that it has no authentication layer and runs tool calls one at a time on the game thread. Epic also says 5.8 is the last planned major UE5 release, with UE6 work ramping up.

What to do: Keep the endpoint on localhost. If you already use a third-party Unreal MCP, check its supported engine versions before moving to 5.8. Flopperam's README, for example, lists 5.5 to 5.7 only.

Tools to check: Unreal MCP (official, UE 5.8, Experimental), EngineWire (ChiR24/Unreal_mcp), Flopperam Unreal Engine MCP, Aura, Ludus AI, runreal/unreal-mcp, unreal-mcp (chongdashu)

Sources: Unreal Engine 5.8 is now available (Epic) · Unreal MCP summary (a2a-mcp.org, third party)

Breaking change Godot · 2026-06-18

Godot 4.7 stable (4.7.1 on Jul 14, 4.7.2 on Aug 18)

Godot 4.7 added HDR output, Control offset transforms, an Asset Store and standalone Android export. Godot's migration guide lists breaking changes to check, including BlendSpace handling, the Audio Spectrum Analyzer API, keyboard and mouse device IDs, particle angular velocity, shader preprocessor restrictions and removal of legacy Android OBB support. 4.7.1 and 4.7.2 are maintenance releases.

What to do: Read the 4.6 to 4.7 upgrade guide before opening a project in 4.7. Then check your Godot MCP or skill pack: Godot AI v4 requires 4.7+, while some tools target 4.6 only (see their tool pages).

Tools to check: Godot AI, Godot MCP bridge (xulek), Codex Godot Skills (fetasty), godot-skills (vl4dt), Godot MCP Full Control (tugcantopaloglu), Godot MCP Pro

Sources: Godot 4.7 release page · Upgrading from 4.6 to 4.7 · Godot releases (GitHub)

News Unreal Engine · 2026-06

Flopperam joins Aura

The Flopperam Unreal Engine MCP repo now carries a banner saying Flopperam has been acquired by Aura and pointing users to tryaura.dev for updates. The repo still contains an open-source local server, but the recommended hosted Flop MCP is a separate product.

What to do: If you rely on the local open-source server in that repo, expect updates there to be slower than the hosted product. Check the repo's commit date on its tool page.

Tools to check: Flopperam Unreal Engine MCP, Aura

Sources: flopperam/unreal-engine-mcp README · Aura 15.0 press release (Business Wire)

Breaking change Unity · Date unknown (Date not stated. Unity's docs page was marked 'last updated 2 months ago' when we read it on 2026-10-23.)

Unity deprecates the in-editor MCP server in favour of the Unity CLI

The MCP server inside the com.unity.ai.assistant package is deprecated. The Unity CLI has its own MCP mode (`unity mcp`) that connects the same way, plus `unity command` and `unity eval` for agents that can run shell commands. Third-party MCP packages installed from GitHub are not affected. Package versions 2.13 and later fix a conflict between the CLI and the in-editor assistant package.

What to do: If you use Unity's built-in MCP server: install the Unity CLI, run `unity pipeline install`, then `unity mcp configure <client>` (for example claude or cursor), and `unity skill install <agent-name>`. Update com.unity.ai.assistant to 2.13 or newer.

Tools to check: Unity AI Assistant MCP server (official, deprecated), Unity CLI (official, with MCP mode and skills)

Sources: Unity CLI as the replacement for the in-Editor MCP server (Unity Docs)

Breaking change Unreal Engine · Date unknown (Date not stated in the README; see the repo's release list.)

Unreal_mcp becomes EngineWire: 0.6 line swaps 23 tools for one `unreal` tool

The ChiR24/Unreal_mcp repository now presents itself as EngineWire. Its README says the 0.6 line (npm unreal-engine-mcp-server@beta, default branch dev) exposes a single `unreal` tool that searches, describes and executes hundreds of capabilities, while the previous stable 0.5.30 (npm latest) exposes 23 separate tools.

What to do: If you upgrade from 0.5.x, follow the README's 'Upgrading from 0.5.x' notes and update your MCP client config, because tool names change. Native HTTP mode needs the X-MCP-Capability-Token header.

Tools to check: EngineWire (ChiR24/Unreal_mcp)

Sources: EngineWire / ChiR24/Unreal_mcp README