After upgrade to Cursor v3.9.16 existing workspaces chat's don't work

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Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I’m unable to continue or start conversation in existing workspace. Same applies in Agents Window. In Editor Window it works but only with new window.

Steps to Reproduce

See description.

Request ID: 1a25db6a-4229-43fc-9a6e-4a35be6ef4e9
No resource accessor found for composer: 3f9dc903-4250-44b3-9ab2-1c8f15f0e4e6
Error: No resource accessor found for composer: 3f9dc903-4250-44b3-9ab2-1c8f15f0e4e6
at Lkh.streamFromAgentBackend (vscode-file://vscode-app/c:/Users/JohannKriek/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:24505:5851)
at Lkh.getAgentStreamResponse (vscode-file://vscode-app/c:/Users/JohannKriek/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:24505:22899)
at IRe.submitChatMaybeAbortCurrent (vscode-file://vscode-app/c:/Users/JohannKriek/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:12142:736)
at async Object.du [as onSubmit] (vscode-file://vscode-app/c:/Users/JohannKriek/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:23548:34996)
at async vscode-file://vscode-app/c:/Users/JohannKriek/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:21445:104651

Operating System

Linux

Version Information

Version: 3.9.16 (user setup)
VS Code Extension API: 1.105.1
Commit: 042b3c1a4c53f2c3808067f519fbfc67b72cad80
Date: 2026-06-27T06:41:01.941Z
Layout: editor
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.256
OS: Windows_NT x64 10.0.26100

For AI issues: which model did you use?

Any and all

Does this stop you from using Cursor

Yes - Cursor is unusable

4

Root cause

Your azure.code-workspace had "folders": [] (an empty multi‑root workspace). That’s why:

  • It only broke in that window (it’s the only one opening that workspace file).
  • New chats, old chats, and MCP‑off all failed identically — the request died before the network (pre_network_to_abort_ms ≈ 20ms, isConnectError: false), with the internal error “No resource accessor found for composer.”
  • “Connection failed” was a misleading label for an internal workspace‑binding failure, not a real network/MCP issue.

Do this now

  1. Go to the broken window and reload it: Ctrl+Shift+P → Developer: Reload Window (or close the workspace and reopen azure.code-workspace).
  2. Chats should work immediately.
  3. You can re‑enable your three MCP servers — they were never the cause.
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Hi @Johann_Kriek Thanks very much for responding back here with your solution. I gave you a badge as a thanks!