Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
updated IDE to latest version, and it failed to connect.
network diagostic screenshot attached.
v3.8.24 user setup does not have this issue, all tests passed on the same system.
it is a Windows 10 system, with system proxy set to an IP address on internal network. the system does not have internet acces on its own.
Steps to Reproduce
- install 3.9.16 on a windows system without internet access, its system proxy set to a local gateway machine with internet access.
- run network diagnostic
- do the same with 3.8.24
Screenshots / Screen Recordings
Operating System
Windows 10/11
Version Information
version 3.9.16 system setup
Does this stop you from using Cursor
Yes - Cursor is unusable
Hey there!
This is a known regression in 3.9.x that affects machines whose only route to the internet is a proxy/gateway. The checks that are failing (API, Ping, Chat, Agent) use a connection type that currently doesn’t route through your system proxy, which is why they show “Network disconnected” while everything else (which does go through the proxy) passes.
The fix is to switch Cursor to the connection type that does honor your proxy:
- Open Cursor Settings → Network.
- Set HTTP Compatibility Mode to HTTP/1.1.
- Fully quit and relaunch Cursor (a full restart, not just Reload Window).
After relaunching, run Run Diagnostics again - API, Ping, Chat, and Agent should pass. You won’t lose any functionality on HTTP/1.1 (agent, chat, and Tab all keep working); the only tradeoff is slightly higher latency. Avoid HTTP/1.0, which is worse.
More detail here: Network troubleshooting - this is something our team is actively looking into. Let me know if HTTP/1.1 gets you back up and running!
