Connection failed after update to latest version

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I updated to version 2.3.9 from version 2.1 and started getting errors like “Connection failed. If the problem persists, please check your internet connection or VPN” at around 30-40% context usage.
If I roll back to version 2.1, the problem goes away.

Steps to Reproduce

Install lataset version and start using agent mode. Fill context to 30-40%.

Expected Behavior

Error doesn’t happens

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.3.9 (system setup)
VSCode Version: 1.105.1
Commit: eecab7538820b6470389330d2cca30b703322290
Date: 2025-12-28T15:39:20.081Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26100

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

2

Hey, thanks for the report. This looks like an interesting issue, a regression between versions 2.1 and 2.3.9.

To dig in, could you share some diagnostic info?

  1. Run Network Diagnostics: Cursor Settings > Network > Run Diagnostics, then share the results.
  2. When the next error happens, copy the Request ID: chat menu (top right) > Copy Request ID.
  3. Open the Developer Tools Console (Help > Toggle Developer Tools) and check if any errors show up when the issue happens.
  4. Which model are you using in Agent Mode?
  5. Are you using a VPN, proxy, or a corporate network?

Also, as a temporary workaround, try disabling HTTP/2: App Settings Ctrl+, > search for “HTTP/2” > enable “Disable HTTP/2”.

Let me know if that helps.