Fusion MCP Server disconnects immediately after initialize - Claude Desktop Windows

[ezouania]

OS: Windows
Claude Desktop: version May 23 2026
Fusion 360: dernière version

Problème : Le serveur MCP Fusion se connecte, reçoit le message
"initialize" de Claude Desktop, puis se déconnecte immédiatement
avec "Server transport closed unexpectedly".

Log typique :
- Server started and connected successfully
- Message from client: initialize (protocolVersion: 2025-11-25)
- Server transport closed unexpectedly
- Server disconnected

Testé : pare-feu désactivé, Node.js v24, redémarrages multiples.
Le problème persiste systématiquement.

[prakharphysics2]

Same issue here, Windows, confirmed via netstat that Fusion is actually listening on 127.0.0.1:27182 — so it's not a firewall/port problem on my end. Log:

[info] Initializing server...

[info] Using built-in Node.js for MCP server: Autodesk Fusion

[info] Server started and connected successfully

[info] Message from client: method="initialize" id=0 params

[info] Server transport closed

[info] Server transport closed unexpectedly, this is likely due to the process exiting early.

[error] Server disconnected.

Tried: full Fusion restart, toggling the extension off/on, checked Scripts and Add-ins for a related add-in (nothing there). Same crash-after-initialize pattern every time, consistently.

[lauri_barnhart]

Hello @ezouania and @prakharphysics.

Thank you for posting your question in the community. Just checking in to see if the issue still exists or if you found a solution to the problem. If you found a solution, please update us here on how it was resolved. If you still need assistance, please provide an update also.

Regards,

[prakharphysics2]

##- First of all I want to say thanks to you for reaching out. The problem
is now resolved.

Was able to figures out the exact cause. It was actually fusion picking a
fresh ephemeral port on every launch rather than honoring 27182. It was all
clear by observing that 127.. URL in the screenshot in API section.

Resolved through Opus 5. Opus 5 is amazing.-##