Agent Host Bridge timeout – Cursor 3.21.16 on Windows

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Problem

Cursor Agent is completely unusable in the IDE. Every time I try to send a message to Agent, it eventually fails with:

Timed out waiting for the agent host bridge to register; please retry.
AgentTurnClassifiedError: Timed out waiting for the agent host bridge to register; please retry.

The error occurs even with a simple request such as:

Hello

Steps to Reproduce

Open Cursor.
Open a project/workspace.
Open Agent in the IDE.
Send any message to Agent.
Wait for the request to complete.

After waiting, Agent fails with the agent host bridge timeout error.

Expected Behavior

Agent should process the request and return a response normally.

Screenshots / Screen Recordings

Captura de pantalla 2026-09-21 114228.png
Captura de pantalla 2026-09-21 114228.png425×248 9.79 KB

Operating System

Windows 10/11

Version Information

Version: 3.21.16 (user setup)
VS Code Extension API: 1.128.0
Commit: 8ae78e8eee1e63479c7e0504b664bc0a80c68000
Date: 2026-09-19T06:43:22.276Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 42.10.0
Chromium: 148.0.7778.280
Node.js: 24.18.1
OS: Windows 11 / Windows_NT x64 10.0.26200

Additional Information

Agent does not start processing the request and eventually returns:

Timed out waiting for the agent host bridge to register; please retry.

The stack trace includes:

_waitForAgentHostBridgeBoundedInner
_waitForAgentHostBridgeBounded
_waitForPushRequestContextProviderRegistration
streamFromAgentBackend
getAgentStreamResponse
Important observations

This problem is not specific to my project.

I have also experienced the same issue on other computers. I initially had Cursor 3.20.21, where I experienced the same error. I then updated to 3.21.16, restarted Windows, and the problem still occurs.

Therefore, the issue persists across Cursor versions and computers.

I have also tested after completely restarting the computer.

I do not see a Cursor Agent Host entry in the Output channels.

Request ID
b60fb08f-d6dd-4a3f-958d-3245926b5db2
Full error
Request ID: b60fb08f-d6dd-4a3f-958d-3245926b5db2
Timed out waiting for the agent host bridge to register; please retry.
AgentTurnClassifiedError: Timed out waiting for the agent host bridge to register; please retry.
at blo (vscode-file://vscode-app/c:/Users/ZG-ENZO-CERFOGLI/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8258:107657)
at async J6o._waitForAgentHostBridgeBoundedInner (vscode-file://vscode-app/c:/Users/ZG-ENZO-CERFOGLI/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:17701:4080)
at async J6o._waitForAgentHostBridgeBounded (vscode-file://vscode-app/c:/Users/ZG-ENZO-CERFOGLI/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:17701:3901)
at async J6o._waitForPushRequestContextProviderRegistration (vscode-file://vscode-app/c:/Users/ZG-ENZO-CERFOGLI/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:17701:3506)
at async cRe (vscode-file://vscode-app/c:/Users/ZG-ENZO-CERFOGLI/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:6917:11698)
at async J6o.streamFromAgentBackend (vscode-file://vscode-app/c:/Users/ZG-ENZO-CERFOGLI/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:17701:10517)
at async J6o.getAgentStreamResponse (vscode-file://vscode-app/c:/Users/ZG-ENZO-CERFOGLI/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:17701:38909)

Could someone from the Cursor team help determine why the Agent Host Bridge is not registering?

This is currently preventing me from using Agent at all.

Does this stop you from using Cursor

Yes - Cursor is unusable

5

Hey, thanks for the detailed report. What you’re seeing means the request isn’t leaving your machine at all. The component the Agent runs inside the editor, Cursor Agent Host, isn’t starting on these computers, so the send fails with a timeout before anything reaches our servers. Not seeing “Cursor Agent Host” in Output is a sign the extension didn’t activate.

This is a known issue on Windows that we’re tracking. To understand why the component isn’t starting on your setup, please send a couple of things from the IDE window where it fails:

  1. Fully close Cursor via File > Exit, then check in Task Manager that there are no cursor processes left.
  2. Reopen the project.
  3. Go to Help > Toggle Developer Tools > Console tab.
  4. Send any message to Agent and wait for the timeout error.
  5. In Console, find the red line that starts with Activating extension 'anysphere.cursor-agent-host' failed, then copy it in full plus the lines right under it.
  6. Go to View > Output, then in the dropdown on the right select “Extension Host” and copy everything that mentions cursor-agent-host.
  7. In File Explorer, check if this file exists and reply yes or no:
    C:\Users\<your user>\AppData\Local\Programs\cursor\resources\app\extensions\cursor-agent-exec\dist\node_modules\@anysphere\tree-chunk-napi\tree-chunk-napi.win32-x64-msvc.node
  8. Are these work or corporate machines with antivirus or endpoint security installed? Also, is Windows Smart App Control enabled at Settings > Privacy & security > Windows Security > App & browser control > Smart App Control?

Send the results here and we’ll dig in. For now, same as before, Cloud Agents launched from the Agents window should work fine for you, so you can use that as a temporary workaround.

8

Hey, an update on this issue. There have been some changes since your report.

The part of Agent that wasn’t starting on your machines, Cursor Agent Host, no longer depends on the Microsoft Visual C++ runtime in the latest version of Cursor. That dependency was a common cause of this timeout on Windows.

Here’s what to try:

  1. Update Cursor to the latest version.
  2. Close it completely through File > Exit. Then check Task Manager to make sure no cursor processes are still running.
  3. Reopen your project and send Agent a short message.

If you can’t update right now, installing or repairing the Microsoft Visual C++ Redistributable x64 package from https://aka.ms/vs/17/release/vc_redist.x64.exe and restarting has helped other Windows users with the same error.

If you still see Timed out waiting for the agent host bridge to register after updating, send us the details from the Developer Tools Console mentioned in the previous message in this thread. We’ll take a closer look.