Unity MCP Pro Tools Cannot Connect Despite Server Running and Unity Editor Connected [need update]

[shadowwarz]

Unity MCP Pro tools fail to connect to Unity editor even when:

External server is running successfully
Unity editor shows "Connected" status in Unity MCP Pro plugin window
WebSocket connections are established on ports 6605-6609
Server shows "Unity editor connected" message

Unity Hub updated to latest version this early morning
Unity MCP Pro tools stopped working after update

[youichi-uda]

Thank you for reporting this issue. To help us investigate, could you provide the following information?

1. Unity version (e.g., Unity 6000.0.x, 2022.3.x)
2. Unity MCP Pro plugin version — visible in the plugin window or package.json
3. MCP server version — check server/package.json or the version shown in your MCP client
4. MCP client — which client are you using? (Claude Desktop, Cursor, VS Code, etc.)
5. Console logs — any errors in the Unity Console window when you try to use a tool?
6. Server logs — any errors in the MCP server stderr output?

You mentioned Unity Hub was updated — did the Unity Editor version itself also change, or only the Hub?

A common cause is a version mismatch between the plugin and server. Please make sure both are from the same release. If you downloaded from itch.io, re-download the latest zip and replace both the plugin and server folders.

Also, try these troubleshooting steps:

1. Close Unity and your MCP client
2. Restart Unity and wait for the plugin to show "Connected"
3. Restart your MCP client
4. Try a simple tool like get_project_info to test the connection