Cursor 3.20.21 stuck on “Reconnecting…” for all models despite Network Diagnostics passing

[Keiku (Keiichi Kuroyanagi)]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Cursor Ask/Agent is stuck indefinitely on “Reconnecting…” and does not return any response.

This suddenly started happening on Sep 15, 2026. Cursor had been working normally in the same environment until today.

The issue occurs even in a brand-new chat with a minimal prompt such as:

Reply only with “hello”.

I reproduced the issue with multiple models, including GPT-5.6 Sol Medium and Claude Opus 5 High.

Interestingly, Network Diagnostics now passes all checks, including Chat and Agent, but actual Ask/Agent requests remain stuck on “Reconnecting…”.

Steps to Reproduce

1. Open Cursor IDE.
2. Start a brand-new Ask/Agent chat.
3. Select GPT-5.6 Sol Medium.
4. Send: Reply only with “hello”.
5. The request remains stuck on “Reconnecting…” indefinitely.
6. Cancel the request and repeat with Claude Opus 5 High.
7. The same issue occurs.

I also tested HTTP compatibility modes HTTP/2, HTTP/1.1, and HTTP/1.0. The actual Ask/Agent request still remains stuck on “Reconnecting…”.

Network Diagnostics passes all checks when using the compatibility setting tested most recently.

Expected Behavior

The model should respond normally to the request instead of remaining indefinitely on “Reconnecting…”.

Screenshots / Screen Recordings

Operating System

MacOS

Version Information

Version: 3.20.21 (Universal)
VS Code Extension API: 1.128.0
Commit: f09fca384ceca23f7bf21f9c23655b162641d740
Date: 2026-09-13T19:02:51.781Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 42.10.0
Chromium: 148.0.7778.280
Node.js: 24.18.1
V8: 14.8.178.38-electron.0
xterm.js: 6.1.0-beta.291
OS: Darwin arm64 25.5.0

For AI issues: which model did you use?

GPT-5.6 Sol Medium
Claude Opus 5 High

The issue reproduces with both models.

For AI issues: add Request ID with privacy disabled

Request ID: fc0fb5db-4c7c-4766-bb40-90813271a755

Additional Information

Additional troubleshooting performed:

• Cursor was working normally in the same environment until Sep 15, 2026.
• The problem started suddenly without any intentional network configuration changes.
• The issue reproduces in a brand-new chat with a minimal prompt.
• The issue reproduces with both GPT-5.6 Sol Medium and Claude Opus 5 High.
• Network Diagnostics currently passes all checks, including Chat and Agent.
• Diagnostic logs show successful SSE responses for Chat and successful bidirectional streaming for Agent.
• macOS system HTTP/HTTPS proxy is not configured (scutil --proxy).
• No proxy environment variables are configured.
• Direct connectivity to api2.cursor.sh works successfully over TLS 1.3 and HTTP/2.
• Tested HTTP/2, HTTP/1.1, and HTTP/1.0 compatibility modes without resolving the actual Ask/Agent issue.
• The actual Ask/Agent UI remains indefinitely on “Reconnecting…”.

Because Network Diagnostics succeeds while real Ask/Agent requests fail across multiple models, this appears to be specific to actual Cursor AI sessions rather than general network connectivity.

Does this stop you from using Cursor

Yes - Cursor is unusable

[mohitjain (Mohit)]

Hey @Keiku! All-green diagnostics but Agent stuck on “Reconnecting…” usually means one thing: is this opened over Remote SSH? On SSH the Agent connects from the remote machine, but diagnostics only test your Mac, so a firewall/proxy/DNS/cert issue on the remote box gives exactly this.

Two quick checks:

1. On the remote machine (plain terminal, not Cursor): curl -sS -o /dev/null -w '%{http_code}\n' --max-time 15 https://api2.cursor.sh/ and same for https://api5.cursor.sh/. A timeout/“could not resolve” = the remote box is blocked (fix its egress/proxy).
2. Open the same project locally on your Mac and send “Reply only with hello” — if that answers, it confirms it’s the remote machine’s network.

[MeLeesa (MeL)]

I am also encountering this issue since 3.20.23. Also, when I check this one “https://api5.cursor.sh/” it fails with “curl: (6) Could not resolve host: api5.cursor.sh
000”.

There are no firewall blocks showing these are being blocked by the firewall or such.

[Jay_Reitz]

I’m having the same issue and it’s rendering Cursor unusable locally. My dev containers disconnect after a few minutes and the only fix is quitting and restarting Cursor.

This is on 3.20.21 and it started a few days ago.

[Keiku (Keiichi Kuroyanagi)]

@mohitjain I use Cursor on an EC2 instance, connecting from my Mac via a bastion server. However, I found that reverting to version 3.19.19 resolved the issue and it is now working correctly. It appears others are experiencing the same problem, so please look into this.

[MeLeesa (MeL)]

The issue has been fixed for me with version 3.21.13+. Seems agent stability issues were introduced with the container/VM features for Projects and Subscriptions, but they are being addressed in 3.21.+ thankfully!