Cursor 3.16.29 Remote SSH severe lag and repeated ptyHost heartbeat failures; 3.14.27 works

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

After upgrading Cursor from 3.14.27 to 3.16.29, Remote SSH became severely laggy on the same server.

The integrated terminal periodically froze, file loading and the Explorer became slow, and the remote Cursor Server logs repeatedly reported:

No ptyHost heartbeat after 6 seconds

This message appeared approximately every 10 seconds. The logs also sometimes contained many messages like:

RequestStore#acceptReply was called without receiving a matching request

Environment:

  • Local OS: Windows 10/11 x64
  • Remote OS: Ubuntu Linux
  • Remote kernel: 5.15.0-186-generic
  • Remote SSH extension versions tested: 1.1.14 and 1.0.50
  • Broken Cursor version: 3.16.29
  • Broken build: 6246455961129c32969845e00aa25d87ae926ec0
  • Working Cursor version: 3.14.27
  • Working build: 047548b00c1a079373d74d00183f32510a4a41e0

I ruled out remote host resource problems:

  • Approximately 2.9 TiB memory was available
  • CPU was mostly idle
  • Approximately 24 TB disk space was available
  • No inode, file descriptor, or process-limit exhaustion
  • Direct file reads took only a few milliseconds
  • Normal SSH remained responsive

Restarting Cursor Server and ptyHost only helped temporarily. Clearing stale sessions, reducing filesystem watchers, excluding large generated directories, disabling terminal persistent sessions, and downgrading only the Remote SSH extension did not resolve the heartbeat failures.

The issue reproduced with a completely fresh Cursor Server 3.16.29 session.

Downgrading the entire Cursor application to 3.14.27 immediately resolved the issue. The remote server switched to build 047548b00c1a079373d74d00183f32510a4a41e0, the repeated ptyHost heartbeat warnings disappeared, and terminal/file responsiveness returned to normal.

This appears to be a regression in the Cursor 3.16.29 remote server PTY/IPC implementation.

Steps to Reproduce

  1. Install Cursor 3.16.29 on Windows x64.
  2. Connect to an Ubuntu 22.04 server with kernel 5.15 using Remote SSH.
  3. Open a remote folder and an integrated terminal.
  4. Use the terminal and browse/edit files for several minutes.
  5. Observe periodic terminal freezes, file-loading delays, reconnects, and repeated “No ptyHost heartbeat after 6 seconds” messages in remoteagent.log.
  6. Downgrade Cursor to 3.14.27 and reconnect.
  7. Observe that the heartbeat errors and lag disappear.

Expected Behavior

Remote SSH terminal input, file loading, and Explorer operations should remain responsive, as they do in Cursor 3.14.27 on the same remote host.

Operating System

Windows 10/11

Version Information

Affected version: Cursor 3.16.29
Affected commit: 6246455961129c32969845e00aa25d87ae926ec0

Current working version after downgrade:
Version: 3.14.27 (user setup)
VS Code Extension API: 1.128.0
Commit: 047548b00c1a079373d74d00183f32510a4a41e0
Date: 2026-08-04T03:29:11.183Z
Layout: IDE
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.291
OS: Windows_NT x64 10.0.26200

Does this stop you from using Cursor

No - Cursor works, but with this issue

5

Hey, thanks for the detailed report. The version bisect with build hashes and the log snippets really help.

This is a known issue we’re already tracking, and I’ve attached your report to it. On Linux servers with a very large CPU count, a periodic system check in the remote server can block it for several seconds at a time. That’s why you’re seeing the terminal freezes and the “No ptyHost heartbeat after 6 seconds” messages about every ~10 seconds. It’s not related to your server or configuration.

There’s a similar thread with the same behavior: [Regression][Remote SSH][Linux] Cursor 3.15.19 blocks server-main for seconds in os.cpus() on high-core-count AMD hosts

For now, the working option is to stay on 3.14.27 like you did. That version doesn’t have this behavior. You don’t need to change anything on the server. I can’t share a timeline yet, but I’ll post here when there’s an update.

8

Hey, back with an update like I promised. The fix for this issue slow Remote SSH and repeated “No ptyHost heartbeat” on Linux hosts with a very large number of CPU cores is ready and will be included in 3.19.10.

Until that version is out, please stay on 3.14.27. That’s still the right option. Once you update to 3.19.10, try again and let me know if the periodic freezes are gone. You don’t need to change anything on the server.