AI assistant problems

AI chat won't start, or the chat page can't connect

Symptom: LLMCHAT reports "Failed to start sidecar", or the chat page opens in the browser but never connects; or chat tools suddenly stop working after you open Claude Desktop / restart chat.

Cause: The chat runs through a small helper program (the "sidecar") launched next to AutoCAD; it can fail to start, get wedged, or end up with stale connection details after a restart.

Fix:

1. Run RECONNECT_DT in AutoCAD. This kills and relaunches the helper and reopens chat — it resolves most wedged states.
2. If chat is missing entirely (no AI Chat button, LLMCHAT unknown/disabled), check %APPDATA%\AutoCADDTPlugin\config.json — "enableLlm": false disables the whole chat surface; remove that line or set it to true, then restart AutoCAD.
3. If you use Claude Desktop / Claude Code / Cursor alongside the in-AutoCAD chat and tools go dead after RECONNECT_DT, restart the MCP connection in that app (e.g., Cursor Settings → MCP → autocad-dt → Restart) — it may be holding stale connection details from before the restart.
4. Only one AutoCAD window can host the chat connection — if you run two AutoCAD instances side by side, chat and MCP tools only work against the first one that loaded the plugin.
5. Still failing? Restart AutoCAD entirely, then send support your log files — launch failures are recorded there with diagnostic detail.

Claude says the autocad-dt server isn't available

AutoCAD probably isn't running — or the assistant didn't start (auto-start can be disabled, or a launch can fail). Open AutoCAD with your drawing, run LLMCHAT (or RECONNECT_DT), then reconnect the server in Claude. Full setup: External MCP clients.

Drawing questions hang or AutoCAD freezes briefly

You (or Claude) may have asked for a full-drawing attribute scan — that forces a slow walk that can block AutoCAD for up to a minute. Narrow to a block, tag, or sheet; see Be specific, not exhaustive.