Windows: Agent host bridge timeout — tree-chunk-napi activation failure in Cursor 3.21.18

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

The local Agent fails across multiple projects in both Cursor IDE and Agents Window, even with a simple “hi”.

Error: “Timed out waiting for the agent host bridge to register; please retry.”

Cursor version: 3.21.18
Request ID: 8f57129c-6931-45a9-aaa2-c920cbd48554

Extension Host logs show:
“Extension activation failure: anysphere.cursor-agent-host”
“Cannot find native binding”
The stack points to @anysphere/tree-chunk-napi/index.js inside cursor-agent-exec.

Restarting, reinstalling, HTTP/1.1, and different models did not resolve it. A separate user-data directory with extensions disabled worked temporarily, but now also fails. Network diagnostics previously passed.

Loading tree-chunk-napi separately using Cursor.exe with ELECTRON_RUN_AS_NODE=1 succeeds, while Agent Host activation fails.

Steps to Reproduce

  1. Open a local project in Cursor on Windows.
  2. Start a new Agent conversation using This PC.
  3. Send “hi”.
  4. Wait until the Agent host bridge registration timeout appears.

The same issue occurs across multiple local projects and in a separate user-data directory launched with extensions disabled.

Expected Behavior

The local Agent should initialize and respond to my message.

Operating System

Windows 10/11

Version Information

Cursor Desktop 3.21.18
Windows
Affects both IDE and Agents Window.

For AI issues: which model did you use?

Claude Opus 5.5 Medium and Auto

For AI issues: add Request ID with privacy disabled

8f57129c-6931-45a9-aaa2-c920cbd48554
Privacy mode status was not verified for this request.

Does this stop you from using Cursor

Yes - Cursor is unusable

5

Hey, thanks for the detailed report and for already ruling out network, reindexing, and extensions. That helps a lot.

This is a known issue on some Windows machines that we’re tracking, and I’ve added your report to it. What’s happening is that the component that starts the Agent locally inside the IDE can’t load one of its native files on startup, so the message never leaves your machine. That’s why you see the agent host bridge timeout. Your account and network are fine, and this isn’t anything you misconfigured.

Your ELECTRON_RUN_AS_NODE test is a good signal here. Standalone loading works, but activation inside the extension host fails. In most cases like this, the cause is a missing or broken Microsoft Visual C++ Redistributable, since the native binding depends on VCRUNTIME140.dll. Please try this:

  1. Install or choose Repair for the latest Microsoft Visual C++ Redistributable x64: https://aka.ms/vs/17/release/vc_redist.x64.exe
  2. Fully close Cursor. Close all windows, then open Task Manager and end any remaining Cursor processes.
  3. Open Cursor, open a local project, start a new Agent chat, and send “hi”.

If it still fails, please send:

  • The full activation error from Help > Toggle Developer Tools > Console. Look for “Activating extension ‘anysphere.cursor-agent-host’ failed”, expand it, and include all the “cause” lines under it.
  • The output of Test-Path C:\Windows\System32\vcruntime140.dll in PowerShell
  • Whether Smart App Control is enabled at Windows Security > App & browser control > Smart App Control

Let me know how it goes.

8

Hey @Invocrew, I’m following up on your report about the agent host bridge timeout.

Since your post, we’ve updated the native component that caused the error. It no longer depends on the Visual C++ runtime, and the fix is in the latest version of Cursor. Cursor 3.24 will add another safeguard so Agent can start even if that component fails to load.

Is the local Agent working for you on the latest version? If it is, there’s no need to reply. If you’re still seeing the timeout, please send the full “cause” lines below the activation error in Help > Toggle Developer Tools > Console. We’ll take a closer look.